36
votes
Accepted
Replacing 80286 with 68000
No, there is no simple one-to-one mapping for the pins. (Bolded signal names will be active-low.)
For example, while the 286 has two physical pins for interrupts (INTR and NMI), 68000 has three (IPL0,...
- 754
27
votes
Accepted
Did any processor have opposite endianness for instructions and data?
First that comes to mind would be Nationals NS16xxx/32xxx series. For data in memory it's little-endian, but displacements and immediate values within instructions are big-endian.
[Official End Of ...
- 232k
20
votes
Replacing 80286 with 68000
Most obvious question first: why not puting itn on a ISA Card and take over the bus instead? Given, there would be still some work to be done after asking for DMA and pulling /MASTER, but way less ...
- 232k
16
votes
Accepted
When was network byte order decided?
As far as I can see, RFC 1700 doesn’t define “network byte order” as a phrase; it specifies the order of transmission of bytes (or octets) on the network, as done previously in the RFCs it obsoletes (...
- 127k
15
votes
Accepted
Which endian was the Intel 4004?
You can find here the Intel 4004 datasheet.
You can see from the 4004 Instruction Set table on page 4 that the 3 nibbles of a jump target address (in ROM) are stored with the highest order nibble in ...
- 6,354
12
votes
Accepted
Swapping endian-ness on the 68000
Swapping byte lanes on the physical bus would, in any case, only have an effect on naturally aligned data in memory, which happened to be the same width as the bus. Swapping the lanes of a 16-bit bus ...
- 16.9k
7
votes
Did any processor have opposite endianness for instructions and data?
The PDP-11 used little endian for most data, and for its instructions. So a normal 16-bit integer, or an instruction like 0xABCD in hex would be stored in two bytes in memory, in ascending address ...
- 14k
7
votes
When was network byte order decided?
For TCP/IP, the matter was "decided" the first time an IP packet was sent. The order of bits and bytes put onto a wire (or a radio link) by the sender had to match the order they were processed by ...
- 11.4k
7
votes
Swapping endian-ness on the 68000
Since you mentioned the Amiga in your question, it ought to be relevant as to how this problem was solved efficiently on that system.
As I understand, the "glue" logic for the Bridgeboards ...
- 61.2k
5
votes
Swapping endian-ness on the 68000
This take a little more circuitry than the OP, in that the byte-swapper has to make use of the Function Code bus lines (FC0, FC1 and FC2) to distinguish between data transfers and instruction fetches. ...
- 13.9k
3
votes
When was network byte order decided?
Network packets are formed once but read during transmission multiple times. Therefore it is worth optimizing reading of multi-byte values. Reading a big-endian unsigned number consisting of N bytes (...
- 20.6k
3
votes
Accepted
Did 68000 on S-100 have any problem with being big endian?
How does this work from the endian-ness perspective?
Endianness is for most parts a software issue. Hardware, especially memory is either agnostic to the way a word ist stored, or doesn't have any ...
- 232k
2
votes
Did 68000 on S-100 have any problem with being big endian?
A long time ago I worked on an Alpha Microsystems computer which was S-100 based little-endian, and while I was there we upgraded to a 68000-based system that had been wired (I don't know the details) ...
- 1,121
2
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Did 68000 on S-100 have any problem with being big endian?
Buses like S-100 are "endianness-agnostic". They do not care about data and its order, they just transport desired content as CPU (or "master") asks. Endianness is "the CPU ...
- 5,585
1
vote
Replacing 80286 with 68000
There were 80286 and 68000 MultiBus system boards. At the bus level they could be interchanged.
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