YAAYD (Yet another "Ten (0A) year" discussion) (was: GOPHER

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Tue Oct 26 22:19:41 2004

> There's even a fair amount of interesting esoteria about the first IBM
> PCs that should be on-topic. I.e.: The very first boxes from IBM had
> painted black power supplies, painted black card-edge plates, and

Not to mention some of the more obscure IBM I/O cards (Profession
Graphics Adapter, Lab I/O, networking, PC/370 processor, etc).

> sported one row of 16Kx1 RAM chips soldered in place, and up to three
> more in sockets, if you ordered more than 16K of memory with your
> system. Also included was the audio-cassette cable, since the first

Was it? I realise original IBM PCs (5150 machines) have the cassette
port, but I thought you were expected to get the cable from RatShack.
The 5 pin DIN socket has the same pinout as the TRS-80...

> PCs (I think up to the 256K motherboards) could be purchased with no
> floppy drives and boot into 'cassette BASIC' in ROM and store and
> recall programs from audio cassette, like many other machines of the
> era.

ROM BASIC is present in the XT and AT too, but with no cassette
interface. I have sometimes wondered about making an I/O card with a BIOS
extension ROM that intercepts INT 15 (IIRC) and, say, uses a paper tape
punch/reader as storage. I think that would work with the ROM BASIC in
the latter machines.

> I doubt if there will be many people posting support questions about
> the dipswitch settings (confusing as hell, they were) for that
> generation of hardware to tell the motherboard how much memory was
> installed, and where (motherboard versus on the I/O channel).

FWIW, I have the IBM TechRefs for the PC, PC/XT and PC/AT machines.

> I also have an all-original IBM-AT box (6 MHz), with IBM's EGA card in
> it, and all IBM hardware throughout. I personally consider it

My AT is much modified, but it still has the IBM Motherboard (with a 486
kludgeboard in the CPU socket...)

I did find a PC/XT system that was 100% IBM. Even has the expansion unit
(containing 2 10Mbyte hard drives...)

-tony
Received on Tue Oct 26 2004 - 22:19:41 BST