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RCA301 was Re: IBM 1401 was: Re: Is it possible to use the value
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| Clark F. Morris, Jr. 2004-06-19, 3:55 am |
| Robert Wagner wrote:
> "Chuck Stevens" <charles.stevens@unisys.com> wrote:
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>
[color=darkred]
> Let's call this hypothetical machine CADET, for Can't Add, Doesn't Even Try. It
> could do arithmetic by table lookup using two indicies. The RCA 301 actually
> worked that way. If someone stepped on the arithmetic table at a fixed address
> in low memory, answers came out wrong until you rebooted the machine.
>
Where were the add tables? I know that the print translate table was in
high memory (19900-63 as I recall) because we had a program space fill
the table causing the Analex (sp?) drum printer to print and blow a
fuse. Translate instructions used tables that started at 00 locations.[color=darkred]
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| Clark F. Morris, Jr. 2004-06-19, 8:55 pm |
| Robert Wagner wrote:
> "Clark F. Morris, Jr." <cfmtech@istar.ca> wrote:
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> It
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> address
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> I don't recall the exact address.
Incidentally, there was no way in assembler to force a 00 starting
address even though one was needed for various tables.
>
> Everything about the RCA 301 (aka ICT1500) seemed like a joke. It had a disk
> drive made by Wurlitzer that looked and worked like a juke box. When an IO error
> occurred, the machine stopped and a red light came on. The operator was expected
> to fix the record in memory (how?) and continue. It had a three-speed card
> reader that required the programmer to start downshifting about a hundred cards
> from the end.
We were lucky because we had the IBM card reader punch attached. The
error correction procedure for tape was to backspace 1 block and then
read it with ALarm Inhibit (ALI) on. The operator would then scan
memory for Memory Register Parity Error and/or Data Parity Error
(MRPE/DPE) and when found, correct the byte in memory.
>
> Perhaps the biggest joke was the tape drives. They were designed with a
> hook-and-eye fastener between the removable tape and the permanent leader. It
> didn't work right, so operators would dismount a tape by cutting it with a pair
> of scissors. The first time I saw that, I couldn't believe my eyes. To mount a
> tape, they'd attach it to the leader with splicing tape.
At Westinghouse Electric International, we actually used the hook and eye.
I did like the RPG they had and DYL260 seemed to be designed with the
same philosophy.
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