56

This is a TrueScan board, which was used for OCR in PC AT systems. The board included a Motorola 68020 CPU, 2 or 4 MiB of RAM, and cost a cool $2,795 for the 2 MiB version (in 1988), $3,995 for the 4 MiB version. You won’t find much by searching for Palantir, because by the time this was available for sale, the company had changed its name to Calera. The ...


20

Yes, part of the POST sequence (which occurs before the display lights up) is a simple memory test which also serves to detect how much RAM is present. The Mac then sets up the hardware and its internal variables to reflect the actual RAM configuration. Attempted accesses of addresses which do not map to memory will either see a dead bus or alias to ...


15

(I was waiting Raffzahn to write an authoritative answer, but he hasn't yet, so I will write it myself.) In General Unless noted, sources are the Guide to Macintosh Family Hardware, 2nd edition, 1990. 680x0 processors expect the reset and exception vectors to reside in low memory (addresses 0x000000 to 0x0003ff). During normal operation, all Macs mapped ...


14

I can suggest why it was created. The Wikipedia page for CPU32 says: The instruction set of the CPU32 core is similar to the 68020 without bitfield instructions, and with a few instructions unique to the CPU32 core, such as table lookup and interpolate instructions, and a low-power stop mode. The objective for CPU32 seems to have been a processor for ...


9

An internal access fault also occurs when the data or instruction MMU detects that a successful address translation is not possible because the page is write protected, supervisor only, or nonresident. (My emphasis.) So, one major case of an internal access fault is an MMU detected condition, where the page is not resident, i.e. a page fault. ...


5

RAM test was common (even ZX48K had it)... How it works: it simply loop through "whole" address space and detects address mirroring and memory bugs. something like: // set system limit max_adr=0xFFFF // clear memory to zero for (adr = 0 ; adr <= max_adr ; adr++) mem[adr] = 0; // test memory is zero and set it to 0xAA for (adr = 0 ; adr <= max_adr ; ...


2

Some machines required dip switches or jumpers. Some used memory probes. The Commodore VIC-20 and C64 used a non-destructive memory probe which would read each address, then try storing two distinct values, observe whether they read back, and then rewrite the address with its previously-read value. Other machines would write all of memory with various ...


2

It seems to me that this statement may be interpreted to mean that Internal Access Faults may happen normally even in a correct program as a side effect of the cache mechanism. I just downloaded the manual: If I interpret it correctly, I would say: No We have to distinguish between cases 1-3 and case 4 described in the manual: If I understand correctly, ...


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