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1500 questions
25
votes
1 answer
How does the NES PlayChoice arcade's security EPROM work?
I've read that the PlayChoice 10's security system includes a 64-bit serial EPROM that gets compared against the first 64 bits of code, and that it's possible to swap the ROMs between compatible cartridges (that use the same mapper) to play…
joeforker
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25
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6 answers
Why did Visual Basic use parentheses for both function call and array access?
In VB both array access and function calls are done with () which makes it difficult to differentiate between those with a quick look. It also makes more nested levels of parentheses like MyArray(GetIndex()) which is much more readable when written…
phuclv
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25
votes
7 answers
What was the last non-monolithic CPU to come to market?
This answer to the question "What was the rationale behind 36 bit computer architectures?" makes the point that early computers were assembled by hand, rather than having central processing units on one chip. The number of CPU bits were chosen…
DrSheldon
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25
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4 answers
When did half-bad RAM chips stop being available?
The ZX Spectrum sold with either 16 or 48K RAM, necessitating an optional 32K memory bank which was achieved in a characteristically (for Sinclair) cleverly frugal way: with half-bad 64kbit DRAM chips, i.e. that had a defect on one half of the chip,…
rwallace
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25
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13 answers
Did computers come with circuit diagrams?
If you purchased a computer, back when they were actually made from discrete components, would you expect to get a circuit diagram as part of the documentation? Was that something you could purchase as an optional extra? Or would you be expected to…
MathematicalOrchid
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25
votes
2 answers
What was the first file system?
SoftwareEngineering.SE has a question about the historically first hierarchical file system (also a similar local question), but what was the first OS with a file system in general?
That is, what OS was the first to abstract the external storage…
Leo B.
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25
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2 answers
What is the massive CD drive used in the movie "Licence to Kill"?
In the movie Licence to Kill, James Bond breaks into Felix Leiter's house and gets a CD out from behind a picture. He then sticks a CD in an absolutely massive CD drive. It was about three times the width of the CD. This movie was released in 1989.…
cup
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25
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2 answers
Why did SCSI require so many pins?
SCSI, I think, is a serial interface. A standard serial port on PCs used a 9-pin DSub connector where a parallel port used a 25-pin connector. Then why did SCSI require so many pins? I vaguely remember 50-pin and 68-pin variants of SCSI. Is it…
Daniel A. White
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25
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2 answers
What is this programming language having PROC, DCL, LABEL keywords?
A 1980 paper called "Register Allocation via Coloring" contains something that looks like source code:
P: PROC(MODE);
DCL
MODE BIT(1),
(A1,A2,A3,A4,A5,A6,A7,A8,A9,A10,
B1,B2,B3,B4,B5,B6,B7,B8,B9,B10,
SUM) FIXED…
KetDog
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25
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3 answers
When connecting to the Internet via Dial-Up, why did ISPs require a username/password to authenticate the session?
It's been many years now, but when I used to connect to the Internet via Dial-Up back in the day I noticed at the time that as well as entering the phone number for my Dial-Up provider, a username/password were also required. Why did Dial-Up…
elliott94
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25
votes
7 answers
Purpose of turbo switch on systems unable to slow to 4.77 MHz?
I have a PC with an Intel P133 (133 MHz). The motherboard (PcPartner MB520NH) only allows for it to be slowed down to 75 MHz at the least via jumper settings, but no lower. Yet the PC's case has an LED module that is configured to show the CPU's…
DBedrenko
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25
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7 answers
What is the reason the 8051 was not used in 8-bit computers?
The 8051 is a Harvard-based microcontroller, but it allows us to connect external memory and simulate von Neumann's architecture. What is the main reason it was not used widely in 1980s home computers?
Was 8051 too late (1980)? Or has it too slow…
Martin Maly
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25
votes
3 answers
Why was it not possible to cost-reduce the Amiga 500?
According to 'Commodore: The Final Years' (whole trilogy highly recommended, BTW), page 129, 'Jeff Porter realized it would not be possible to significantly cost reduce the Amiga 500 to get it into the $250 retail price range'.
This is really…
rwallace
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25
votes
1 answer
Reconstruct the loop from "The Story of Mel"
From Ed Nather's hacker-epic "The Story of Mel" (using the original paragraph-formatting to save space in this question):
The firm manufactured the LGP-30, a small, cheap (by the standards of the day)
drum-memory computer, and had just started to…
Quuxplusone
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25
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1 answer
MOS 8502, just a 6510B?
I'm looking over what little I can find on the 8502, and from what I can see it appears to be a 2 MHz version of the 6510 with an extra I/O pin.
Much ado about the speed, but the Atari's 6502B's were doing 2 MHz years earlier, and the BBC Micro as…
Maury Markowitz
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