I thought that the SD controller board set was also bit slice (the series II internal was of course 8271 based). They handled the same comands at a different I/O location. The only format difference between SD and DD was the DD was proprietary of course and had 52 sectors instead of 26. That made the OS software easy to handle either density rather than creating blocking schemes that CP/M did which would require more software handling. Intel kept ISIS low in memory and had a program load address that did not let you make the OS any bigger than when ISIS first came out. The advantage was that as long as you had 32K of memmory you could run any Intel software and putting 30K more of memory in the system was immediately available (unlike cp/m).
The floppy interface for the bit slice was pretty well abstracted in that the cpu wrote commands to I/O ports and the data off disk was dma'd to and from memory. You told it what to do, where to put it, and how much to data. The cpu didn't have to do anything else except wait for completion of the operation.
-----Original Message-----
From: "Joe R." <rigdonj(a)cfl.rr.com>
Sent: Oct 30, 2004 10:20 AM
To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk(a)classiccmp.org>
Subject: Re: new find: an Intel MDS 800
That's interesting. I've never even heard of a white MDS-800 before. Was
it painted white originally or was it painted over an orginal blue one?
I think you need a lot more than rewriting the BIOS to handle DD disks.
Intels DD controller has a 3000 series bit-slice CPU and some other odd
circuitry to handle DD.
Joe
Hi Megan,
>from the mails I've got it is clear that the DECpc 320p supports
just a few hard disk types and these are "hard-coded" in the BIOS.
Worse: even the utility to access the BIOS does not support any
change of the few known hard disk types.
A few days ago was a good explanation of how a Disk Manager works,
and that's what I did. You need a floppy to boot (MS)DOS and the
OnTrack Disk Manager of the hard disk manufacturer or the OnTrack
version that accepts any brand. The first one for a specific disk
manufacturer can be found on various sites, the latter one must be
bought.
Step 1. install the new hard disk (*any* storage size, as long as
the disk fits physically :-)
Step 2. have an *empty* floppy available. Skip if you're always lucky...
Step 3. boot to DOS from the boot floppy.
Step 4. start Disk Manager (DM.EXE) from the OnTrack floppy.
DM detects the disk geometry and presents something else to the BIOS
so that the BIOS can work with the disk. Without OnTrack the BIOS does
not know how to read the disk, so better make a bootable copy on the
floppy mentioned in step 2 when OnTrack asks if you'd like to do that!
- Henk, PA8PDP.
-----Original Message-----
From: cctalk-bounces(a)classiccmp.org
To: General Discussion: On-Topic Posts Only
Sent: 30-10-2004 8:16
Subject: RE: access to BIOS of DECpc
>I feel a bit silly, but it was late last night is my excuse.
>"DECpc 320P" in Google gave a link to floppy images on a COMPAQ site.
>I will try them this evening, but it is good to know that the DECpc
>"knows" a limited number of hard disks. If I can 'upgrade' to some
>300 Mb of the 420 Mb capacity it is still better than the 40 Mb that
>I have available at this point.
Years ago, I found out what I thought to be sufficient info to
upgrade my 320P from the 40mb drive it had, to a 120mb I had
been able to obtain... apparently type 46 and type 47 in the
BIOS are user definable. And I guess I didn't have all the
info, or I touched the wrong area because I essentially 'bricked'
my 320p. It no longer boots.
If you do find out how to do it reliably, I'd be interested in
trying to fix it.
Megan Gentry
Former RT-11 Developer
+--------------------------------+-------------------------------------+
| Megan Gentry, EMT/B, PP-ASEL,ST| email: mbg at world.std.com |
| Member of Technical Staff | megan at savaje.com |
| SavaJe Technologies, Inc. | (s/ at /@/) |
| 100 Apollo Drive | URL: http://world.std.com/~mbg/ |
| Chelmsford, MA 01824 | "pdp-11 programmer - some assembler |
| (978) 256 6521 (DEC '77-'98) | required." - mbg KB1FCA |
+--------------------------------+-------------------------------------+
Photo at:
http://home.earthlink.net/~pkaneko/data_io_stuff.jpg
Andybody need/want this?
The socket adaptors are:
715-1039
715-1028-1
715-1035-2
The fourth plug-in says that it is a calibrator program adaptor . . . .
Jeff
Does anybody have any of the old "Beta 20" 5 1/4" 20Mb Bernoulli disks
that they're willing to part with? I picked up a Bering HP-IB drive that
I'd like to test.
Joe
>I feel a bit silly, but it was late last night is my excuse.
>"DECpc 320P" in Google gave a link to floppy images on a COMPAQ site.
>I will try them this evening, but it is good to know that the DECpc
>"knows" a limited number of hard disks. If I can 'upgrade' to some
>300 Mb of the 420 Mb capacity it is still better than the 40 Mb that
>I have available at this point.
Years ago, I found out what I thought to be sufficient info to
upgrade my 320P from the 40mb drive it had, to a 120mb I had
been able to obtain... apparently type 46 and type 47 in the
BIOS are user definable. And I guess I didn't have all the
info, or I touched the wrong area because I essentially 'bricked'
my 320p. It no longer boots.
If you do find out how to do it reliably, I'd be interested in
trying to fix it.
Megan Gentry
Former RT-11 Developer
+--------------------------------+-------------------------------------+
| Megan Gentry, EMT/B, PP-ASEL,ST| email: mbg at world.std.com |
| Member of Technical Staff | megan at savaje.com |
| SavaJe Technologies, Inc. | (s/ at /@/) |
| 100 Apollo Drive | URL: http://world.std.com/~mbg/ |
| Chelmsford, MA 01824 | "pdp-11 programmer - some assembler |
| (978) 256 6521 (DEC '77-'98) | required." - mbg KB1FCA |
+--------------------------------+-------------------------------------+
Hi Marvin
If you come across one of the small serial cards, I'm
looking for one for my Poly88. It doesn't need parts, just
the board would be great.
Have you been able to get a Poly 88xx system up and running
yet? If not, you should still bring a controller card, cables
and drives for the 8 inch setup. I think I have the 5-1/4"
setup covered. I'll blow some ROMs with the updates to handle
the 8 inch drives.
I'll be heading out soon and won't be on the net again until
Monday.
Dwight
>From: "Marvin Johnston" <marvin(a)rain.org>
>
>
>With VCF comming up in about 8 days, I am planning on bringing a bunch
>of stuff up there to get rid, er, sell :). In that vein, is there
>anything special those of you who will be attending are looking for? My
>plan is to reduce my collection to things that are primarily in the 70's
>to very early 80's, and I will mostly concentrate on CP/M and S-100
>systems.
>
>Things I have that are not in my area of interest or expertise include:
>
>SparcStatation2 w/ external CD-ROM, Color Monitor, Keyboard, Mouse,
>Working
>Wang computer (don't remember model), about 10"w x 24"h x 30"d.,
>untested
>Xerox computer, Model 8???, w/ monitor/keyboard. About the same size as
>the Wang, untested
>Phillips computer, about 24"w x 24"h x 30"d w/ 8" drive(s), untested
>
>Make a reasonable offer, but I won't be bringing the above stuff unless
>someone wants it!
>
>As usual, I'll post a link to the list of stuff that I'll be bringing
>up.
>
Is http://www.classiccmp.org/ down? I've been trying to log into the web
site since last night, and can't connect. I seem to recall that there
was a problem with the HD, but I don't recall the actual server being
down. BTW, being on digest mode, I won't see any responses unless I log
into the site, get an email, or wait until the digest gets processed and
sent out.
---------- Forwarded message ----------
From: David Forbes
I was reading that 1961 BRL survey, and found the user reports
of the IBM 701 fascinating. They apparently had an average
uptime of about 2-4 hours. That doesn't seem like much by
today's standards, but then how often does Windows crash on you?
The amazing thing is how much they paid per calculation. $50,000
rental per month for a typical installation at 500 multiplies per
second is about 10,000 multiplies per dollar! We seem to get a
better price these days with a typical PC. It's about a trillion
multiplies per dollar, which is a factor of 100 million better.
--
--David Forbes, Tucson, AZ
http://www.cathodecorner.com/