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Well the 1800 finally arrived from Canada on 6th March 2004, along with many other interesting items. (In addition to the 1800 & peripherals, there was a nice working pdp-8/l, with a Honeywell tabletop paper tape reader - the 8/l seems to be working fine, but the paper tape reader has 'issues' - RIM is toggled in, when started the reader reads, but BIN is not correctly loaded. Dropped bits somewhere... ho hum. There's also an IBM 129 card punch, an IBM 083 card sorter, and a nice pdp-8/f with PC04 and LA30 Decwriter, in a 'short' rack. Oh and a pdp-10 - a Decsystem 2065 ;-)

The 1800 is serial number 10694:



Not uncommonly for IBM machines, it proclaims itself to be the property of IBM; these machines were frequently leased rather than bought outright initially.

'1802' on the faceplate, but '1801' inside... hmmmm. Perhaps it was upgraded? The difference between an 1802 and a standard 1801 CPU, according to an old a.f.c. post, is that the 1802 had logic to talk to a 2401 tape drive.


Here are some fairly 'raw' quick & dirty pics... SLT porn! Click on any of the pictures to the full-size high-resolution original.



Here's the 1800 with front doors open, just off the truck. Panel on the right, logic gates, core, power supply (bottom) on the left.




The blinkenlights.




Behind the panel... more logic gates!




Under the steel covers on the logic gates... SLT cards. The entire machine is SLT - just like the System/360.




The cover of one of the core assemblies... 8k of core.




Inside, the core stack (centre), and much SLT logic.




The two left-side logic gates folded out, exposing the backplanes. Six SLT backplanes per gate, four gates in the machine, a potential 72 logic card positions per backplane, -> 4 x 6 x 72 = a potential 1728 individual SLT cards to make up the machine... now not every position is occupied, and some cards are double-width or larger, and the core takes up some space... but it's still a bloody lot of cards!




With both left-side gates folded out, you can see what's in the rear part of the left side of the machine: the entire space from top to bottom is taken up by the power supply





The rear doors open. The entire left side is power supply, the panels on the right are for the connections to the various D/A & A/D devices that could be hooked-up, I think - I haven't read the manual. Yet. The lower part on the left side contains the bus & tag connectors for channel devices.

There's reason to fear the power supply; here's the power data plate:



208V, 3-phase, 60 amps! Flaming Nora! That's as bad as the pdp-10, or worse!


The load device that came with the system is the IBM 1442 card reader/punch - the cheap & nasty interrupt-driven low-end reader.




At least it's in a matching shade of red...




It's a bit mucky inside & out; Kevin Stumpf allegedly removed a dead mouse from it some time ago
(he had been storing (very patiently - thanks Kevin!) the machines for me for some time). Nothing a good cleaning won't fix.
Note (typical IBM) all the required manuals have a storage position *inside* the machine. Also the bus & tag channel interface cables.

I intend to hook this up to my S/390 at some point; it will be fun giving VM a *real* punch instead of a virtual one!
And I can use it on my System/360, if & when the damned thing ever arrives...




The pretty trivial logic assembly. IBM's philosophy for this one would seem to have been 'do it all in software - use CPU cycles'.
Totally unbuffered, just a 'raw' channel interface.




Inside the mechanics. not in bad shape, considering the age. A little cleaning & rubber restorer...




The 1053 console printer. Not sure how the operator talked back to the system. I know it could support a 1052 printer/keyboard
(or, I've read, the 'heavy-duty' option for the 1800 was the 1816?), and I would dearly love to find one.
If you have a clue where I might find one, please email me! I'll even pay a real cash bounty, if required.




Inside... typical Selectric mechanism


That's all for now... more pictures, scans, and restoration progress reports to follow!