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Old 2008-09-12, 01:27   #12
Wacky
 
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Quote:
Originally Posted by cheesehead View Post
it had a card reader.
Do you mean those bits of pasteboard with round holes in them?

I also remember "programming" with wires.
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Old 2008-09-12, 02:49   #13
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Default oh yeah?

I once read an EPROM's content, disassembled and groked the (Z-80) code, and then found a way of applying patches to a batch of preprogrammed remaining EPROMs - the basic trick was to turn some instruction (before the bug) into a CALL (or a JMP) into some leftover free space (which was all FFs) and continue the correct code there, execute some code and RET (or JMP back). (on a EPROM you can only turn '1's to '0's; so we could program over the burnt EPROMs with the patch code)

Perfocards are boring and wouldn't shock as many people as the matrix memory image:
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Old 2008-09-12, 06:15   #14
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My first computer had a tape drive as an add-on. I bought a 300 buad modem. I punched 5 1/4" floppies.

I have manually rebuilt the FAT entry for a lost file, cluster by cluster.

I have also called up an equipment manufacturer to ask, "Is it possible to sub and return between program areas and have things work ok?", their response, "What ever are you doing? Can you send us a copy when you get it done and working?"

What is this SIM stuff? my first memory upgrade was 9 chips onto the motherboard.
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Old 2008-09-12, 07:30   #15
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My first computer was a UK101 with a 1MHz 6502 CPU and 2KB of ram.
I remember soldering a wire from the 5v output of the transformer onto the NMI interrupt & writing a machine code routine counting the 50 interrupts to increment each second for a clock routine.

Regards
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Old 2008-09-12, 07:54   #16
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Quote:
Originally Posted by Patrick123 View Post
My first computer was a ... a 1MHz 6502 CPU ...
You had it easy!

The first computer at my school had 8kB of core memory (see Batalov's post).

When the paper tape reader for it broke, I disassembled all 3 meters of the bootstrap tape for it. I discovered that only first 25 cm of it had code, the remaining 2.75 meters had a banner print routine. Until the paper tape reader got fixed I had an exclusive use of the machine. I just keyed in the first 25cm of the bootstrap tape using the sense switches, everything else came out of RK05-compatible 1.5MB disc drive. Obviously (for me, but not for the class-mates or the teachers) the banner was irrelevant.
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Old 2008-09-12, 08:19   #17
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Yes, those guys. Unfortunately I don't have any Zilogs, but I still have a 27256 my shelf. (Started indeed with 2764's = 8Kb, this one below is 4 times larger. The whole 64Kb!!)

Believe it or not, but a discrete 8-bit real time fourier processing was done with the program in 8kb of memory (not to be confused with FFT; a simple convolution of 1-bit zero-crossing data from a comparator with 0V was done with 6 base frequencies, sine and cosine; the "bus" frequency was 4MHz, but any simplest operation on Zilog took 4 cycles, and many, much more, so all of that had to be kept in mind for a tight coupling with the carrier frequency. Not so many registers were there (some were coupled in 16-bit register pairs!), but we've managed.
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Old 2008-09-12, 10:25   #18
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Quote:
Originally Posted by sylvester View Post
8kB of core memory
That's too "modern".
The LGP30 had a rotating magnetic drum for the main store. You used to carefully select where the next instruction was stored in order to minimize access latency.

But that, too, was modern. How about a memory that was full of Hg?
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Old 2008-09-12, 11:10   #19
xilman
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Quote:
Originally Posted by Wacky View Post
Do you mean those bits of pasteboard with round holes in them?

I also remember "programming" with wires.
BTDT. In my case, the patch panel on an IBM card reader.

Paul
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Old 2008-09-12, 15:04   #20
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This is the one that I fiddled with in all my sparetime at college. I could usually pinoint a hardware problem in a matter of seconds. But when current draw was too high in too many places at once it was a B****.
much like wacky's LGP30.

http://en.wikipedia.org/wiki/Bendix_G-15

nelson
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Old 2008-09-12, 15:50   #21
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You all had electricity?

:surprised
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Old 2008-09-12, 16:00   #22
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I guess this board doesn't have anyone old enough to trump us all by saying: "My first job title was computer."
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