MC6800 processor - Page 1
Forum section: electronics / general

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: February 15, 2021, 06:48:04 pm
content: Hope this is the right place for this questionWhat programmer can I use to program a Motorola MC68A00 chip?I have a TL866 for EPROM.Wally

author: ataradov
author_rank: Super Contributor
timestamp: February 15, 2021, 07:12:50 pm
content: It does not have any internal memories. There is nothing to program.

author: coppice
author_rank: Super Contributor
timestamp: February 15, 2021, 07:21:00 pm
content: Quote from: Wallace Gasiewicz on February 15, 2021, 06:48:04 pmThe MC68A00 is a microprocessor. That is, its just a CPU with memory buses to the outside world. There is no memory. There are no peripherals. There is nothing in it to program.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: February 15, 2021, 08:49:35 pm
content: Thanks,I thought there was some intrinsic memory.It is for repair of an HP 3456. There is memory on the board which is good.Thank you all for the help.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: February 18, 2021, 09:02:00 pm
content: Are all the 68A00 chips identical , if they are Mitsubishi or Motorola are they the same or is there something I should be aware of?Wally

author: srb1954
author_rank: Super Contributor
timestamp: February 19, 2021, 12:53:11 am
content: Quote from: Wallace Gasiewicz on February 18, 2021, 09:02:00 pmThe 6800 series was second-sourced by several manufacturers and should basically be plug compatible if the application circuit was designed in accordance with the original Motorola datasheet. There may be subtle differences in the chips between different manufacturers but these shouldn't affect normal operation of the chip.Where you might run into trouble is when the designer has used some undocumented feature in the chip or pushes it past the datasheet specifications or selects the chip for specific performance parameters. In this case you can expect some second-source chips might not work as intended. This is unlikely to the case if you are looking at HP designed equipment.

author: coppice
author_rank: Super Contributor
timestamp: February 19, 2021, 02:03:43 am
content: Quote from: srb1954 on February 19, 2021, 12:53:11 amThe 6800 family was produced as a true second source by several manufacturers, which you can rely on as being truly equivalent. This includes at least Philips, Thomson (ST), and Hitachi. However, I don't think Mitsubishi made 6800 family parts.

author: srb1954
author_rank: Super Contributor
timestamp: February 19, 2021, 05:06:56 am
content: Quote from: coppice on February 19, 2021, 02:03:43 amI spent a good deal of my first year as an electronics engineer debugging troublesome 6800 systems and I found that there were subtle differences on how second source chips from different manufacturers behaved. The 6800 system was initially developed using Motorola parts and all seemed fine. But when production transferred to cheaper AMI second-source parts there were a lot of random field failures. As it turned out in the final analysis it was the support circuitry around the 6800 that wasn't up to scratch and not the processors themselves.Nevertheless the different brands behaved differently with the dodgy support circuit. This may have been down to manufacturing process variations or it may have been that AMI slightly relaxed their test specifications to get a better production yield and a lower chip price.Quote from: coppice on February 19, 2021, 02:03:43 amI don't recall Philips second-sourcing the 6800. They did second source the 68000 and a number of 68000 peripheral chips.

author: coppice
author_rank: Super Contributor
timestamp: February 19, 2021, 02:11:32 pm
content: Quote from: srb1954 on February 19, 2021, 05:06:56 amYou would have noticed similar things with genuine Motorola parts made at different times, as they refined their processes and made them faster. Most equipment makers are pretty sloppy about tracing how the devices they use vary from batch to batch. There can be radical changes, like moving to a much finer process, that has all sorts of effects on a board's performance.