24 Oct
2007
24 Oct
'07
5:35 p.m.
I bought an RL disk pack on Ebay, supposedly for an RL02 drive. It
is a Memorex "Mark III T" with a small label "Made in USA CI
04050" and various previous-owner stickers/scribbles showing first
use in 1983 up through 1985. The shock indicator is not red.
But it won't load in any of my four RL02 drives (the Ready light
never comes on, so track 0 is not being found)!
Since the drive has embedded servo info, so head alignment between
drives is not an issue, there are only two remaining possibilities
that I can think of:
1) the pack is defective (factory servo tracks are trashed), or
2) it is an RL01 (5 Mb) pack, which looks physically identical but
will not work in an RL02 drive.
Any thoughts... Would this be the likely result (no Ready light)
of putting an RL01 pack in an RL02 drive? If so, anyone want to
buy it (or preferably trade for the proper pack)?
thanks
Charles
24 Oct
24 Oct
5:49 p.m.
On 10/25/07, Charles <charlesmorris at hughes.net> wrote:
I bought an RL disk pack on Ebay, supposedly for an
RL02 drive. It
is a Memorex "Mark III T" with a small label "Made in USA CI
04050" and various previous-owner stickers/scribbles showing first
use in 1983 up through 1985. The shock indicator is not red.
I have seen non-DEC RL packs in the past, but didn't DG or someone use
the same shell for their own drives, too?
1) the pack is defective (factory servo tracks are
trashed)...
Defective, or bulk-erased, which amounts to the same thing.
I don't recall what happens when you try to mount an RL01 pack in an
RL02, but you _might_ get an error light rather than just not get a
ready light.
You could hook a scope to some amplified head signal and at least
verify that there is *some* signal coming from the pack. That might
help eliminate bulk-erased media from consideration.
Perhaps someone with an old media company catalog might be able to
check order info for the Memorex pack, but ISTR the best days of the
RL01 were long behind it by 1983, which would make me initially expect
that it probably was some other cause than RL01 vs RL02 issues,
leaving "blank media" or "non-DEC media" as likely issues.
-ethan
8:54 p.m.
Charles wrote:
Any thoughts... Would this be the likely result (no
Ready light)
of putting an RL01 pack in an RL02 drive? If so, anyone want to
buy it (or preferably trade for the proper pack)?
I have Qbus systems with both RL01 and RL02 drives. I'll experiment
with the improper media and each drive and post the results later tonight.
- Jared
9:28 p.m.
J Blaser wrote:
Charles wrote:
Did a couple of quick tests with these results:
RL02K cart in RL01 drive:
- spins up okay, and READY lights up
- using RT11, a DIR produces: ?DIR-F-Error reading directory[1]
RL01K cart in RL02 drive:
- spins up okay, and READY lights up
- using RT11, a DIR produces a full directory listing just fine![2]
So, if the OP is not seeing the READY light, then the cart is probably
not formatted for DEC equipment, as Al suggested. I'm not sure that
there is any way to make that cart DEC compatible, since DEC formatted
these RL carts at the factory, and as I understand it, there is no field
formatter, nor is the drive capable of doing a format in the first place.
- Jared
[1] I haven't calculated, but probably because the directory 'spills'
over into unexpected blocks at the end of the 'expected' RL01 directory
segment.
[2] Looks okay, but then once the head seeks past track 0, we'd be
doomed! Tracks on the RL02K carts are twice as narrow as those on the
RL01K carts and the RL01 drive would skip the physical track 1 and try
to use track 2, thinking it is track 1.
Any thoughts... Would this be the likely result
(no Ready light)
of putting an RL01 pack in an RL02 drive? If so, anyone want to
buy it (or preferably trade for the proper pack)?
I have Qbus systems with both RL01 and RL02 drives. I'll experiment
with the improper media and each drive and post the results later
tonight. 
25 Oct
25 Oct
11:56 a.m.
I bought an RL disk pack on Ebay, supposedly for an RL02 drive. It
is a Memorex "Mark III T" with a small label "Made in USA CI
04050" and various previous-owner stickers/scribbles showing first
use in 1983 up through 1985. The shock indicator is not red.
But it won't load in any of my four RL02 drives (the Ready light
never comes on, so track 0 is not being found)!
Since the drive has embedded servo info, so head alignment between
drives is not an issue, there are only two remaining possibilities
that I can think of:
1) the pack is defective (factory servo tracks are trashed), or
2) it is an RL01 (5 Mb) pack, which looks physically identical but
will not work in an RL02 drive.
Any thoughts... Would this be the likely result (no Ready light)
of putting an RL01 pack in an RL02 drive? If so, anyone want to
buy it (or preferably trade for the proper pack)?
It may not be an RL pack at all. Several other companies made top-loading
disk drives that used similar-looking packs, which were not servo-tracked
at all. I seem to rememebr seeing one for the PDP11, I think it was
norminally RK05-compatile.
Often these other drives had a different number of sectors to the RL's as
well. Have you tried counting the notches in the flange of the hub?
If you put one of thse packs into an RL, it never goes ready. Or the
ready lamp flickers.
-tony
6:34 p.m.
New subject: Altair 8800 Help
Hello, all,
I recently acquired a very nice Altair 8800 with 40K of RAM (1 non-MITS
16K Static RAM board, and 3 MITS 4K Static RAM Boards, a MITS Version 1
8080 CPU Board, a MITS 2SIO, a MITS 88-DCDD floppy disc controller (two
board pair), a MITS PROM board (8-slots for 1702 256-byte PROMS), a MITS
4-port Parallel card, and two MITS 8" floppy disc drive enclosures,
along with a Televideo 912 Terminal, a heavily modified CT-1024
"TV-Typewriter", and a serial TI 810 printer, and an 18-slot (non-MITS)
motherboard with an upgraded power supply. That along with boatloads of
spare parts, a bus extender, a couple of unused S-100 bus prototyping
cards, an unstuffed Ithaca Audio S100 board (not sure what it is), all
of the original Altair documentation, a bunch of 8" floppies (including
original various version of MITS (Micro-soft) BASIC, MITS DOS, and
FORTRAN complier, and a bunch of documentation written by the former
owner of the system.
I very carefully inventoried everything first, then pulled out all of
the boards from the CPU and tested out the power supply, first
un-loaded, then under dummy loads, then powered it up with the front
panel power leads connected, but no other boards, and all looked good.
Then I plugged in the CPU board and the 16K static RAM board, and
powered up and could reliably examine and deposit data into the RAM. I
then wrote some simple test programs and toggled them in, such as
reading the sense switches and storing their content into a memory
location, setting all (as much of possible without getting too fancy) of
memory to a specific value, then verifying it, and various other CPU
functionality tests.
All the little test I did passed with flying colors. I then added in
the three 8K MITS RAM boards, and they all seemed to work fine also.
Then I plugged in the 2SIO board, but didn't have a cable to connect the
port clearly configured on the board as the console port to the
terminal, so I've got some work to do there. Tonight, I'm hoping to
write a little test code using HYPERTERM or the like on a laptop to
read/write characters through the console port. The other port is
configured strangely, and I need to do some jumper wire tracing to
figure out how it's configured.
So, the CPU itself seems great. Next, I checked out the floppy
controller boards, making sure all of the chips were well-seated (they
were all socketed), and checked the power supply lines and regulators to
make sure they were OK.
Put the board set into the system, plugged "DRIVE 0" into the CPU, and
toggled in some very basic floppy controller functionality tests that
are included in the manual for the controller, and tried out the tests.
They all passed just fine per the results that should be obtained as
mentioned in the manual.
So, here's the dilemma. The PROM board is currently configured at a
start address of 1 111 100 000 000 000 (174000 Octal, or 0xF800). I
plugged all of the PROMs into the sockets (there were five different
ROMs that I found, including one that had a label that indicated that it
was some kind of BOOT ROM). I started examining memory at 0xF800, and
found that most all of the PROMs contained all zeros...either erased, or
suffering from failure due to extreme age (date codes of '76), and/or
no covers over the windows. The one PROM that responded was the one
that had the label hinting that it might be a boot PROM. So, I wrote
down the content of the PROM and went about hand disassembling it. It
does indeed appear to talk to the floppy controller, which is hard-coded
at I/O Addresses 0x10, 0x11, and 0x12), as there are a lot of IN and OUT
instructions referencing these I/O addresses. Looking at the various
absolute jump addresses in the ROM, it appers to be coded to run at
0x4Cxx, or 046xxx Octal. If I set the start address of the ROM board to
make this ROM appear in the proper place, it'll conflict with the RAM
installed in the system.
I have a number of disks which I'd like to try to boot from, including:
ALTAIR DISK EXTENDED BASIC
REVISION 4.1 JUNE 1977
COPYRIGHT 1988 BY MITS INC.
Another disk with the following:
MITS DISK OPERATING SYSTEM (DOS)
VERSION #1.0 MFG: 03/13/78
COPYRIGHT 1977 BY MITS INC.
FLOPPY DISK
(NWD) SN: 10396
Which also has a label below this one saying
FORTRAN COMPILER
VERSION #2.8 MFG:06/05/78
COPYRIGHT 1978 BY MITS INC.
COPYRIGHT 1978 BY MICROSOFT INC.
(NWD) SN: 10152
Also on this same disk is a small label saying:
(C)MICROSOFT 1977
ALBUQUERQUE, NEW MEXICO
And another disk that says:
ALTAIR COMPUTER CENTER
BEAVERTON, OREGON
DISK COPY UTILITY VERSION 2.0 14-APR-78
SN: 10058 7808
NOTE: THIS DISKETTE WILL NOT COPY ITSELF
All of the labels on these disks are original manufacturer
labels...these disks are the genuine thing, not copies.
Clearly, I'd love to be able to boot these disks. I think that the
floppy controller is good. The system even came with a Alignment Disk,
so I toggled in some of the routines that would allow observation of the
tracking (cats-eye) and index/sector (it's a hard-sectored controller)
stuff with an oscilloscope, and everything looked perfect.
I just need some bootstrap code. I've looked around in all of the
documentation, and there's no boot code listed in the docs for the
floppy subsystem. There are small bootstrap routines to load code over
the 2SIO board (presumably from a paper-tape reader on an ASR-33 TTY),
another from a parallel port (presumably from one of those little
optical tape readers that you'd pull the tape through, wasn't it a
company called OAE?), and another from cassette (but I don't have an
interface board for cassette). I've thought of writing a small program
that would copy the boot code out of the PROM into the proper space
within RAM, and then JMPing to it, but not sure if that'll work or
not...I suppose it's worth a try, but haven't done that yet.
I've perused the web a lot looking for boot code for the Altair floppy
controller, and haven't been able to find anything.
Any Altair experts out there that might have some floppy boot code for
the Altair 88DCDD floppy controller that might work to boot up the MITS
DOS, or DISK EXTENDED BASIC floppies I've got? Also, anyone know the
default console port I/O address that these products expect the serial
console to be at? I assume the FORTRAN compiler runs under MITS DOS,
and that's why the two products are together on the same disk. Right
now I've only got one of the floppy drives connected up, but I'd expect
that the FORTRAN compiler will need the 2nd drive in order to do
anything useful, but I'm trying to take things one step at a time.
I've got a manual for Altair DOS, and it does describe the disk format,
so I suppose I could write a boot program myself, but it'd be a lot
easier just to find someone that already has the stuff.
Also, if anyone knows where Altair DOS and Disk Extended BASIC expect
the serial console (e.g, I/O Port Address), that too would be helpful.
If anyone could help, I'd sure appreciate it.
Thanks in advance,
Rick Bensene
The Old Calculator (and sometimes Computer) Museum
http://oldcalculatormuseum.com
6:52 p.m.
New subject: Altair 8800 Help
Rick:
Congrats on a great acquisition.
4k BASIC requires a console at ports 0/1 but you could configure later
BASICs (8k, 12k and Disk Extended) to accept other configurations by setting
the front panel toggles properly.
If you look on my emulator site (http://www.altair32.com) you will find
the instructions for booting BASIC (they are actually contained in the help
file for the emulator).
As far as booting the floppy disk is concerned, I think one of the
folders in the emulator distribution has the code for the disk bootstrap in
it. If not, here's what I have. This is used in the 88-DSK emulation to boot
Altair disk images.
Since you have a real operating machine, it'd be great if I could get
binary copies of any interesting disks for the archive and see if I can get
them to boot on the emulator.
Rich
--
Rich Cini
Collector of Classic Computers
Build Master and lead engineer, Altair32 Emulator
http://www.altair32.com
http://highgate.comm.sfu.ca/~rcini/classiccmp
;the altair rom moves this code to 4c00h then jumps to it
;this is a disassembly of the 4c00h code
;C crc on disk doesn't match calculated crc
;M memory error read/back from memory doesn't match
; write to memory (no ram or bad ram)
;O overflow or out of mem caused by trying to load beyond
; ff00 or bad "load limit bytes" on disk.
4C00 DI ;disable interrupts
4C01 LXI SP,4D62 ;load stack pointer
4C04 XRA A ;ZERO IN A
4C05 OUT 08 ;SELECT DRIVE 0
4C07 MVI A,04 ;HEAD DOWN CMD
4C09 OUT 09 ;SEND head down
4C0B JMP 4C19 ;GO TEST FOR TRACK ZERO
4C0E TMVOK: IN 08 ;GET STATUS
4C10 ANI 02 ;TEST FOR MOVE OK
4C12 JNZ 4C0E ;JMP MOVE NOT OK
4C15 MVI A,02 ;step out cmd
4C17 OUT 09 ;send step out
4C19 TTRK0: IN 08 ;GET STATUS
4C1B ANI 40 ;TEST FOR TRACK ZERO
4C1D JNZ 4C0E ;JMP NOT TRACK ZERO
4C20 LXI D,0000 ;DE->0000H
4C23 NXTTK: MVI B,00 ;B=0
4C25 THDDN: IN 08 ;GET STATUS
4C27 ANI 04 ;TEST FOR HEAD DOWN
4C29 JNZ 4C25 ;JMP NOT HEAD DOWN
;SEEK TO SECTOR IN B
4C2C NXTSEC: MVI A,10 ;A=10H 16D RETRY COUNT
4C2E RETRY: PUSH PSW ;SAVE RETRY COUNT
4C2F PUSH D ;NXTMEM
4C30 PUSH B ;B=SECTOR
4C31 PUSH D ;NXTMEM
4C32 LXI D,8086 ;D=80(UNUSED?) E=128=COUNT
4C35 LXI H,4CD4 ;M=POINTER TO INBUFFER
4C38 TSECT: IN 09 ;GET SECTOR# UNDER HEAD AND STATUS
4C3A RAR ;TEST SECTOR TRUE
4C3B JC 4C38 ;jmp TSECT if not true
4C3E ANI 1F ;and sector mask 31d
4C40 CMP B ;DESIRED SECTOR
4C41 JNZ 4C38 ;jmp TSECT if not equal
;READ 134 BYTES TWO AT A TIME INTO INBUFFER
4C44 TRDOK: IN 08 ;get status
4C46 ORA A ;set flags test for read ok
4C47 JM 4C44 ;jmp TRDOK if not read ok
4C4A IN 0A ;get data byte1
4C4C MOV M,A ;move BYTE TO INBUFF
4C4D INX H ;BUMP INPOINTER
4C4E DCR E ;decrement COUNT
4C4F JZ 4C5A ;jmp MVBYTS if DONE
4C52 DCR E ;dec COUNT
4C53 IN 0A ;get data byte2
4C55 MOV M,A ;move to INBUFF
4C56 INX H ;increment POINTER
4C57 JNZ 4C44 ;jmp TRDOK if count in E is not zero
;MOVE 128 DATA BYTES FROM BUFF TO MEMORY MAKE A CRC
4C5A MVBYTS: POP H ;hl (M)=0000h first time
4C5B LXI D,4CD7 ;DE POINTS TO BUFFER + 3
4C5E LXI B,0080 ;B=0=CRC C=128 count
4C61 MVBYT2: LDAX D ;GET BYTE FROM BUFFER
4C62 MOV M,A ;MOVE TO DESTINATION
4C63 CMP M ;CHECK FOR MEMORY PROBLEM
4C64 JNZ 4CC1 ;JMP MERROR if problem
4C67 ADD B ;make a crc
4C68 MOV B,A ;save in B
4C69 INX D ;inc src
4C6A INX H ;inc dest
4C6B DCR C ;dec count
4C6C JNZ 4C61 ;jmp MVBYT2 until count = 0
;CHECK CRC
4C6F LDAX D ;DE POINTS TO BUFFER + 131
4C70 CPI FF ;COMPARE THAT BYTE TO 255
4C72 JNZ 4C78 ;JMP FFERR IF NOT EQUAL
4C75 INX D ;INC DE POINTS TO BUFF+132
4C76 LDAX D ;GET THAT BYTE
4C77 CMP B ;COMPARE TO CRC
4C78 FFERR: POP B ;B=SECTOR
4C79 XCHG ;DE->NEXT DEST HL->BUFF+132
4C7A JNZ 4CB5 ;CRC ERROR GO CRCERR
;CHECK FOR OUT OF MEMORY CHECK DONE LOADING
4C7D POP PSW ;0000H FIRST TIME
4C7E POP PSW ;ACC=16
4C7F LHLD 4CD5 ;L=BUFF+1 H=BUFF+2
4C82 PUSH D ;SAVE NEXT DEST 0080 first time
4C83 LXI D,FF00 ;DE->BOOTROM(END OF MEMORY)
4C86 CALL 4CCE ;COMPARE1 FF00H,HL OUT OF MEMORY (HL GREATER THAN
FF00H)
4C89 POP D ; NEXT DEST
4C8A JC 4CBE ;JMP 'O'UT OF RAM ERROR (HL GREATER THAN FFOOH)
4C8D CALL 4CCE ;COMPARE2 DE,HL ARE WE DONE LOADING?
4C90 JNC 4CAE ;IF NO CARRY (HL <= NEXT DEST)WE'RE DONE GO EXECUTE
;CALCULATE NEXT SECTOR AND TRACK
4C93 INR B ;ADD 2 TO SECTOR#
4C94 INR B ;
4C95 MOV A,B ;DESIRED NEXT SECTORA
4C96 CPI 20 ;TEST IF SECTORA LESS THAN 32
4C98 JC 4C2C ;IF LESS GO GET IT
4C9B MVI B,01 ; IF NOT LESS MAKE DESIRED SECTORB=1
4C9D JZ 4C2C ;IF SECTORA EQUALED 32 GO GET SECTORB=1
4CA0 IN 08 ;ELSE GET STATUS
4CA2 ANI 02 ;TEST MOVE OK
4CA4 JNZ 4CA0 ;UNTIL MOVE IS OK
4CA7 MVI A,01 ;STEP IN CMD
4CA9 OUT 09 ;SEND STEP IN CMD
4CAB JMP 4C23 ;START LOADING FROM NEXT TRACK SECTORB=0
;load the even sectors on a track first
;then the odd sectors
;DONE
4CAE MVI A,80 ;
4CB0 OUT 08 ;CLEAR CONTROLLER
4CB2 JMP 0000 ;GO
;CRC ERROR RETRY PSW TIMES
4CB5 CRCERR: POP D
4CB6 POP PSW ;
4CB7 DCR A ;DECREMENT RETRY COUNT
4CB8 JNZ 4C2E ;IF NOT 0 GO RETRY
;CLEAR CONTROLLER SEND TO CONSOLE ERROR MESSAGE
4CBB MVI A,43 ;ELSE LOAD A WITH CHAR 'C'RC ERROR
4CBD LXI B,4F3E ;GARBAGE
;4CBE MVI A,4F ; LOAD A WITH CHAR 'O'verflow
4CC0 LXI B,4D3E ;GARBAGE
;4CC1 MERROR: MVI A,4D ; LOAD A WITH CHAR 'M'EMORY ERROR
4CC3 MOV B,A ;SAVE CHAR
4CC4 MVI A,80 ;CLEAR CONTROLLER
4CC6 OUT 08 ;SEND CLEAR
4CC8 MOV A,B ;GET CHAR
4CC9 OUT 01 ;SEND error char TO CONSOLE
4CCB JMP 4CC9 ;OVER AND OVER and over...
;TEST FOR OVERFLOW, TEST load limit, COMPARE HL,DE
4CCE MOV A,D ;
4CCF CMP H ;
4CD0 RNZ ;
4CD1 MOV A,E ;
4CD2 CMP L ;
4CD3 RET
;BEGINNING OF IN BUFFER
4CD4 ADD H
On 10/25/07 9:34 PM, "Rick Bensene" <rickb at bensene.com> wrote:
Hello, all,
I recently acquired a very nice Altair 8800 with 40K of RAM (1 non-MITS
16K Static RAM board, and 3 MITS 4K Static RAM Boards, a MITS Version 1
8080 CPU Board, a MITS 2SIO, a MITS 88-DCDD floppy disc controller (two
board pair), a MITS PROM board (8-slots for 1702 256-byte PROMS), a MITS
4-port Parallel card, and two MITS 8" floppy disc drive enclosures,
along with a Televideo 912 Terminal, a heavily modified CT-1024
"TV-Typewriter", and a serial TI 810 printer, and an 18-slot (non-MITS)
motherboard with an upgraded power supply. That along with boatloads of
spare parts, a bus extender, a couple of unused S-100 bus prototyping
cards, an unstuffed Ithaca Audio S100 board (not sure what it is), all
of the original Altair documentation, a bunch of 8" floppies (including
original various version of MITS (Micro-soft) BASIC, MITS DOS, and
FORTRAN complier, and a bunch of documentation written by the former
owner of the system.
I very carefully inventoried everything first, then pulled out all of
the boards from the CPU and tested out the power supply, first
un-loaded, then under dummy loads, then powered it up with the front
panel power leads connected, but no other boards, and all looked good.
Then I plugged in the CPU board and the 16K static RAM board, and
powered up and could reliably examine and deposit data into the RAM. I
then wrote some simple test programs and toggled them in, such as
reading the sense switches and storing their content into a memory
location, setting all (as much of possible without getting too fancy) of
memory to a specific value, then verifying it, and various other CPU
functionality tests.
All the little test I did passed with flying colors. I then added in
the three 8K MITS RAM boards, and they all seemed to work fine also.
Then I plugged in the 2SIO board, but didn't have a cable to connect the
port clearly configured on the board as the console port to the
terminal, so I've got some work to do there. Tonight, I'm hoping to
write a little test code using HYPERTERM or the like on a laptop to
read/write characters through the console port. The other port is
configured strangely, and I need to do some jumper wire tracing to
figure out how it's configured.
So, the CPU itself seems great. Next, I checked out the floppy
controller boards, making sure all of the chips were well-seated (they
were all socketed), and checked the power supply lines and regulators to
make sure they were OK.
Put the board set into the system, plugged "DRIVE 0" into the CPU, and
toggled in some very basic floppy controller functionality tests that
are included in the manual for the controller, and tried out the tests.
They all passed just fine per the results that should be obtained as
mentioned in the manual.
So, here's the dilemma. The PROM board is currently configured at a
start address of 1 111 100 000 000 000 (174000 Octal, or 0xF800). I
plugged all of the PROMs into the sockets (there were five different
ROMs that I found, including one that had a label that indicated that it
was some kind of BOOT ROM). I started examining memory at 0xF800, and
found that most all of the PROMs contained all zeros...either erased, or
suffering from failure due to extreme age (date codes of '76), and/or
no covers over the windows. The one PROM that responded was the one
that had the label hinting that it might be a boot PROM. So, I wrote
down the content of the PROM and went about hand disassembling it. It
does indeed appear to talk to the floppy controller, which is hard-coded
at I/O Addresses 0x10, 0x11, and 0x12), as there are a lot of IN and OUT
instructions referencing these I/O addresses. Looking at the various
absolute jump addresses in the ROM, it appers to be coded to run at
0x4Cxx, or 046xxx Octal. If I set the start address of the ROM board to
make this ROM appear in the proper place, it'll conflict with the RAM
installed in the system.
I have a number of disks which I'd like to try to boot from, including:
ALTAIR DISK EXTENDED BASIC
REVISION 4.1 JUNE 1977
COPYRIGHT 1988 BY MITS INC.
Another disk with the following:
MITS DISK OPERATING SYSTEM (DOS)
VERSION #1.0 MFG: 03/13/78
COPYRIGHT 1977 BY MITS INC.
FLOPPY DISK
(NWD) SN: 10396
Which also has a label below this one saying
FORTRAN COMPILER
VERSION #2.8 MFG:06/05/78
COPYRIGHT 1978 BY MITS INC.
COPYRIGHT 1978 BY MICROSOFT INC.
(NWD) SN: 10152
Also on this same disk is a small label saying:
(C)MICROSOFT 1977
ALBUQUERQUE, NEW MEXICO
And another disk that says:
ALTAIR COMPUTER CENTER
BEAVERTON, OREGON
DISK COPY UTILITY VERSION 2.0 14-APR-78
SN: 10058 7808
NOTE: THIS DISKETTE WILL NOT COPY ITSELF
All of the labels on these disks are original manufacturer
labels...these disks are the genuine thing, not copies.
Clearly, I'd love to be able to boot these disks. I think that the
floppy controller is good. The system even came with a Alignment Disk,
so I toggled in some of the routines that would allow observation of the
tracking (cats-eye) and index/sector (it's a hard-sectored controller)
stuff with an oscilloscope, and everything looked perfect.
I just need some bootstrap code. I've looked around in all of the
documentation, and there's no boot code listed in the docs for the
floppy subsystem. There are small bootstrap routines to load code over
the 2SIO board (presumably from a paper-tape reader on an ASR-33 TTY),
another from a parallel port (presumably from one of those little
optical tape readers that you'd pull the tape through, wasn't it a
company called OAE?), and another from cassette (but I don't have an
interface board for cassette). I've thought of writing a small program
that would copy the boot code out of the PROM into the proper space
within RAM, and then JMPing to it, but not sure if that'll work or
not...I suppose it's worth a try, but haven't done that yet.
I've perused the web a lot looking for boot code for the Altair floppy
controller, and haven't been able to find anything.
Any Altair experts out there that might have some floppy boot code for
the Altair 88DCDD floppy controller that might work to boot up the MITS
DOS, or DISK EXTENDED BASIC floppies I've got? Also, anyone know the
default console port I/O address that these products expect the serial
console to be at? I assume the FORTRAN compiler runs under MITS DOS,
and that's why the two products are together on the same disk. Right
now I've only got one of the floppy drives connected up, but I'd expect
that the FORTRAN compiler will need the 2nd drive in order to do
anything useful, but I'm trying to take things one step at a time.
I've got a manual for Altair DOS, and it does describe the disk format,
so I suppose I could write a boot program myself, but it'd be a lot
easier just to find someone that already has the stuff.
Also, if anyone knows where Altair DOS and Disk Extended BASIC expect
the serial console (e.g, I/O Port Address), that too would be helpful.
If anyone could help, I'd sure appreciate it.
Thanks in advance,
Rick Bensene
The Old Calculator (and sometimes Computer) Museum
http://oldcalculatormuseum.com
Rich
--
Rich Cini
Collector of Classic Computers
Build Master and lead engineer, Altair32 Emulator
http://www.altair32.com
http://highgate.comm.sfu.ca/~rcini/classiccmp
7:52 p.m.
New subject: Altair 8800 Help
So, here's the dilemma. The PROM board is
currently configured at a
start address of 1 111 100 000 000 000 (174000 Octal, or 0xF800). I
plugged all of the PROMs into the sockets (there were five different
ROMs that I found, including one that had a label that indicated that it
was some kind of BOOT ROM). I started examining memory at 0xF800, and
found that most all of the PROMs contained all zeros...either erased, or
suffering from failure due to extreme age (date codes of '76), and/or
no covers over the windows. The one PROM that responded was the one
that had the label hinting that it might be a boot PROM. So, I wrote
down the content of the PROM and went about hand disassembling it. It
does indeed appear to talk to the floppy controller, which is hard-coded
at I/O Addresses 0x10, 0x11, and 0x12), as there are a lot of IN and OUT
instructions referencing these I/O addresses. Looking at the various
absolute jump addresses in the ROM, it appers to be coded to run at
0x4Cxx, or 046xxx Octal. If I set the start address of the ROM board to
make this ROM appear in the proper place, it'll conflict with the RAM
installed in the system.
I have most of the boot PROMs and I also have a way of programming them.
The disk boot rom goes in the far right slot. I think it copies
itself into ram before running.
Your ROM card is set up for the correct addresses as is.
Flip A15-A8 up, do examine, flip all down except A11, then run. Your
system should boot. You should at least get a noise out of the disk
drive. You should have at least 24k of RAM to be safe. It won't
sound anything like the emulator... ; )
I have detailed pictures and descriptions on how to wire the 2SIO as
well as programs for checking it out.
There are 3 pages here:
http://www.stockly.com/forums/showthread.php?t=507
Grant
11:15 p.m.
New subject: Altair 8800 Help (Follow-Up)
Thanks to Rich and Grant for the information they promptly posted.
This led me to put the supposed boot PROM in the right-most slot in the
ROM board, and try booting.
I got nowhere. Thought I'd try single stepping a bit, and noted that
With the boot PROM is in this socket, it always reads back 11111111 for
all addresses within the 256-byte address space. If I move the PROM to
one of the lower-addressed sockets (further to the left end of the
board), the PROM data shows up properly in that PROM socket's address
space.
So, what I think I've got going on is that either the 74157 address
decoder has bad outputs for chip enable on the highest-addressed ROM, or
the discrete-transistor-based Vgg power switching drivers that control
the -9V supply (based on diode-AND-gated pairs of outputs from the
74157) to the upper two PROMs is bad. This Vgg switching based on
"turning on" banks of two PROMS at a time is a power-saving measure.
Time to break out the scope and start looking around.
Both Rich and Grant pointed out that the ROM actually copies most of
itself into RAM beginning at 0x4C00, and then branches to the
RAM-resident code. I'd overlooked this in my hand disassembly, as I was
mostly looking to find the references to the IN and OUT instructions
that talked to the floppy controller, as well as branch addresses, which
was confusing in the context of the code executing directly out of the
PROM. Looking more carefully at what I dumped out of the PROM (when it
was located in a socket on the ROM board where I can actually read it),
it's clear that it does a copy of a chunk of the PROM image, executing
this copy code out of the PROM, into RAM beginning at 0x4C00, then
branches to 0x4C00 after the copy is completed, to actually do the boot
from disk executing the boot code in RAM.
I'll keep the list posted as to progress.
-Rick
26 Oct
26 Oct
10:33 a.m.
New subject: Altair 8800 Help (Another Follow-Up)
An update on the Altair:
Rather than try to debug the problem with the ROM board, I just moved
the boot PROM to the lowest address socket, leaving the board select
address at 0xF400, and wrote a tiny program to copy the correct part of
the PROM into RAM at 0x4C00, as the beginning code in the boot PROM
does. Put an infinite loop at the end of the little copier so I could
check on the copy.
First time around, the copy wasn't working. Diagnosed to be a problem
on one of the 8K RAM boards. Removed that board for now, and
reconfigured the two remaining 8K RAM boards so there was no gap in the
address space, resulting in 32K in the machine.
Tried again, and now I could see the boot code properly copied into
0x4C00.
Next, I did some tinkering, and figured out that the low port on the
2SIO board was configured at the correct default I/O address. Tinkered
with some RS232 cables I had, along with null modem/gender benders to
get a cable that resulted in garbage being displayed on the Televideo
912C terminal that came with the system when the CPU was powered on.
Then wrote some little tests to make sure I could send and receive
characters from the terminal, which worked just fine.
So, I re-entered the little "copy" routine, ran it, then halted the
machine from the infinite loop at the end of the copy code, reset the
CPU, set the address switches to 0x4C00, put the Altair Disk Extended
BASIC disk into the floppy drive, held my breath, and flicked "RUN".
The drive immediately loaded the head at Track 0, lights on the front
panel were blinking like crazy, then the drive advanced the head to
track 1, and then track 2, then suddenly, on the terminal, I see "MEMORY
SIZE?"!!!
I ran through the initial dialog, and was able to MOUNT disk 0, then do
a RUN"PIP", and see the directory of the disk. Since this was an
original disk, I didn't attempt to write anything to it. The only
things on the disk are "PIP" and "STRTREK". Can't run STRTREK
because
the machine doesn't have enough RAM for it. With Disk Extended BASIC
loaded, the machine reports 3072 bytes free after the initial dialog,
where I told the system to allow up to 3 open files at once, and 2
random files at once. I'm sure that if I set it to 1 and 0, there'd be
considerably more space left for user programs, but probably still not
enough for STRTREK. I need to figure out what is up with the sick 8K
RAM board, so I can get the machine back to 40K.
While rummaging through the stuff in the boxes of stuff I got with the
machine, I found a couple more interesting things. A spare 2SIO board,
2 original MITS 4K RAM boards (I think these were the very trouble-prone
first generation dynamic RAM boards, which is why they probably aren't
used), and a bare board made by "wmc Inc." entitled "MEM-1", revision
C,
with a date of 1977. This appears to be a Wameco 8K Static RAM board
that uses 2101A RAMs.
No wonder it has four places for 7805 Voltage Regulators with heat
sinks. I found an assembly guide on the Web, may go ahead and build it
out. I've got a good stash of 2102's, and the rest of the support logic
I probably have in my cache of old TTL chips.
The unpopulated Ithaca Audio board is an IA-1010, and looking around on
the web, it's a Z80 CPU board for the S-100 bus. It is a very
nicely-made board, with full solder mask, and nice silkscreen. So far,
haven't been able to find any assembly information for this board,
though it'd be interesting to build out and try. I think I've got a
couple of Z80 chips around here, and probably enough parts to populate
it.
Things to do:
1) Figure out the problem with the ROM board
2) Try to fix the busted 8K RAM board
3) Build a cable to connect the floppy DRIVE 0 chassis to the DRIVE 1
chassis (so I can run both drives)
4) Start exploring all of the other floppies that came with the system
5) Check out the TI 810 printer and see if I can get it hooked up to the
system and working
6) Do some tinkering with the TV Typewriter, and see if it's functional,
though with all the mods, it'll be a bit of a challenge.
So far, I'm pretty encouraged with how things are going. None of the
problems found thus far are showstoppers .
Comments & suggestions are welcomed, either (if appropriate) by posting
here, or sending me Email off-list.
Rick Bensene
The Old Calculator Museum
http://oldcalculatormuseum.com
11:10 a.m.
New subject: Altair 8800 Help (Another Follow-Up)
On 26 Oct 2007 at 10:33, Rick Bensene wrote:
An update on the Altair...
Congratulations on getting the thing running! I'm surprised that the
old capacitors in the power supply haven't dried out yet--but I
suspect that you have a heavier-duty PSU in your box--the original
didn't have much spare capacity.
Yup, the 4K DRAM boards were miserable--they had an annoying tendency
to change contents when "Reset" was pressed. Still, if you feel the
urge to try them, I have some Fujitsu clones of the original 4K TI
chips that you can have that might hold onto data better.
On the other hand, the boards that used 2102 or even 21L02 SRAMs were
pretty power hungry.
I never used MITS-DOS; I became disgusted with the lousy production
quality of the 8800 and moved to an IMSAI box for a time, then to an
Integrand "no blinky lights, not even a power indicator" box and ran
CP/M.
Cheers,
Chuck
11:39 a.m.
New subject: Altair 8800 Help (Another Follow-Up)
So, I re-entered the little "copy" routine, ran it, then halted the
machine from the infinite loop at the end of the copy code, reset the
CPU, set the address switches to 0x4C00, put the Altair Disk Extended
BASIC disk into the floppy drive, held my breath, and flicked "RUN".
The drive immediately loaded the head at Track 0, lights on the front
panel were blinking like crazy, then the drive advanced the head to
track 1, and then track 2, then suddenly, on the terminal, I see "MEMORY
SIZE?"!!!
Put an AM radio next to the computer with the lid off and it will
sound crazy when you are running programs off of disk. Instant
Sci-Fi movie effect.
I've written a program that transfers the disks into a computer for
archival and preservation. Are you interested in using it to save
your disks? The disk images are compatible with the Altair32 emulator.
I've used it to image very sensitive disks with many errors. I was
able to go through the disk on my windows machine and extract information.
Grant
6219
days inactive
6220
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12 comments
9 participants
participants (9)
-
ard＠p850ug1.demon.co.uk -
cclist＠sydex.com -
charlesmorris＠hughes.net -
ethan.dicks＠gmail.com -
grant＠stockly.com -
oldcpu2＠rogerwilco.org -
rcini＠optonline.net -
rickb＠bensene.com -
wdonzelli＠gmail.com