17 Aug
2006
17 Aug
'06
3:58 p.m.
I don't know if it's any use to you, but
_years_ ago I wrote a Turbo
Pascal program (runs under MS-DOS) to read double-density PERQ
'interchange' floppies on a PC. As set up, it's designed to use a
secondary controller in the PC (the XT on my desk has such a controller
linked to a pair of 8" drives...).
If you're interested (or if anyone else is interested) I can dig out the
source code. I seem to remeber the original distribution terms were that
I hold the copyright, but 'further distribution for the benefit of PERQ
fanatics is encouraged).
I'd definitely be interested in having the software for future use; as
it currently stands I don't have any software on
floppies to read so I
won't have much use for it. (Plus I still need to get an 8" floppy
You can, of course, transfer data from the hard disk to a floppy on the
PERQ ;-).
connected to a PC, I have one sitting around for the
job but haven't
gotten around to hooking it up yet.)
Or you could link a 5152" 1.2M floppy drive to the PERQ in place of the
8" one. I have info on the cable I made to do that...
Using a 5.25" 1.2Mbyte floppy disk with the PERQ
------------------------------------------------
Data Cable
PERQ EIO 5.25" Drive
1 o
2 o
3 o
4 o
5 o
6 o
7 o
8 o
9 o--Gnd-----+
10 o--2 side--+
11 o
12 o
13 o-----Gnd--------------------o 31
14 o-----Head Select------------o 32
15 o
16 o
17 o
18 o
19 o-----Gnd--------------------o 7
20 o-----Index------------------o 8
21 o-----Gnd--------------------o 33
22 o-----Ready------------------o 34
23 o
24 o
25 o-----Gnd--------------------o 11
26 o-----Drive Sel 0------------o 12
27 o
28 o +----Gnd---------------o 15
29 o +----Motor On----------o 16
30 o
31 o
32 o
33 o-----Gnd--------------------o 17
34 o-----Direction--------------o 18
35 o-----Gnd--------------------o 19
36 o-----Step-------------------o 20
37 o-----Gnd--------------------o 21
38 o-----Wr Data----------------o 22
39 o-----Gnd--------------------o 23
40 o-----Wr Gate----------------o 24
41 o-----Gnd--------------------o 25
42 o-----Trk 00-----------------o 26
43 o-----Gnd--------------------o 27
44 o-----Wr Prot----------------o 28
45 o-----Gnd--------------------o 29
46 o-----Rd Data----------------o 30
47 o
48 o
49 o
50 o
Construction
1) Crimp 34 pin IDC edge connector to one end of 1m length of multicoloured IDC
ribbon cable, so that pin 1 is connected to the first brown wire, and pin 34 to
the last yellow wire.
2) At the other end of the cable, separate the wires between :
6,7 (blue,violet)
8,9 (grey, white)
10,11 (black, brown)
12,13 (red, orange)
14,15 (yellow,green)
16,17 (blue, violet)
30,31 (black, brown)
32,33 (red, orange)
3) Make the wide section (wires 17-30) about 8 cm long, by tearing back the
other sections.
4) Crimp wires 17-30 (violet - black) to pins 33-46 of a 50 pin IDC edge
connector. Remove the top part of the connector after crimping so that other
wires can be added.
5) Similarly crimp 31,32 (brown and red) to 13,14 of the 50 pin edge connector,
33,34 (orange, yellow) to pins 21,22, 7,8 (violet, grey) to pins 19,20 and 11,12
(brown, red) to pins 25,26.
6) Crimp a short spare length of IDC wire between pins 9 and 10 of the 50 pin
edge connector. Fit the top part, and press it firmly into place.
7) Cut off wires 1-6 (brown-blue), 9,10 (white, black), and 13,14 (orange,
yellow).
8) Strip wires 15,16 (green, blue), and twist them together. Solder the
connection, and insulate it with a short length of Heat-shrink sleeving
Power Cable
-----------
+5V and +12V to operate the floppy drive can be obtained from the Tablet Power
Connector on the rear of PERQ2 machines. A suitable cable is given below.
Check the connections to the floppy drive to make sure you have the +5 and +12
the right way round before you apply power. Some drives have the connections
marked on the PCB.
4pin DIN (Plug Wire Side) Floppy Drive
+--------- +5V ---------------------------(4
|
o1
o---- +12V ---------------------------(1
o
o
|
+--------- Gnd ---------------------------(2
+--------- Gnd ---------------------------(3
Drive links
-----------
Set the drive to respond to Drive Select 1 (the default for PC drives)
The PERQ will boot from floppy if the Ready pin (pin 34 of the 34 pin connector)
is held low when th edrive is selected, and will not use the drive under any
circumstances if the ready pin is high when the drive is selected.
Some drives allow a Ready signal to be output on this line, often by setting an
internal link. If this is possible, do it. Otherwise, _try_ connecting the ready
input on the PERQ to the Drive Select output via a SPST switch. Close this
switch when there is a floppy in the drive
Notes
-----
The PERQ checks for the drive being ready _before_ asserting the Head Load
Signal, and thus the head load output cannot be used to drive the Motor On
input. By tying the Motor On input low, the drive motor runs whenever there is a
floppy in the drive. This is a good compromise, but may cause wear of the disk
and heads if left there for an extended period. Do not leave a floppy disk in
the drive if it is not being used
The 2-side input of the PERQ is pulled low, so that the disk is assumed to be
double sided.
The cable links the top connector on the EIO board to a standard 1.2Mbyte 5.25"
floppy. Pin 1 is at the top of the EIO board.
The PERQ 8" drive rotates at 360rpm, as do 1.2Mbyte drives. However, tests have
shown that a 300rpm drive will also work, although not all of its capacity will
be used. Therefore, a 3.5" 1.44Mbyte drive is another possibility.
If you need
any help with accessing the hard disk, etc, I may well have
useful information around. I certainly have things like the I/O port map,
etc.
Definitely; I believe I have something working (it's chugging along as
we speak) using POS system calls; I've just uploaded the source of my
program to my site (
http://yahozna.dhs.org/computers/software/PERQ/dumpdisk.pas). Go easy
on me, it's both my first Pascal program and my first PERQ program, and
Don't worry, I don't claim to be a programmer, I release source to stuff
I've written mainly to give programmers a good laugh...
I haven't cleaned it up much. Might be useful for
other people
interested in preserving the contents of their drives.
AFAIK doscuemtnation for just about everything exists. There are full
schematics for most machines (I think the 2T4 is missing). PROM/PAL dumps
exist. Commented sources to the bootstrap ROMs and EIO Z80 ROM exist. I
am not sure if there are sources for the Z80 ROM on the PERQ 1's CIO
card, I can see (but I do know that the CIO and EIO ROMs are _very_
different).
Good luck. The PERQ is not a simple machine at
all. Having managed to
understand how the CPU works, I'd not want to try emulating it...
And a PERQ 2 would be even worse. On that series, you can run user code
on the I/O processor (Z80)....
-tony
Yeah -- like I said, we'll see how it turns out :). There seems to be a
lot of available documentation on the system (microcode, etc...) so I'm hoping that's enough to get a good start -- and
you sound like the
person to ask if it's not :).
Feel free....
-tony