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Well.... Crystal frequency is 4xE so E is not 1843.2 KHz but 921.6 KHz --> 57600 baud. 😁 Problem solved ! Thanks to those that try to help.

Yes I agree... I just want to be the most possible sure that the problem is not elsewhere. I am a very distracted so check and recheck is my only option.

On 6502.org forum a user say his MC68B50 work with the same configuration as mine (with the same 1843.2 KHz signal on E pin and rx-tx clock pins)... I will continue to search !

Hi All, I have a serial interface for a home build Flex computer made with a MC68B50. This chip need a bus timing sync clock named E and a separate rx-tx clock. The rx-tx clock can be provided by an output of a 6522 via (CB1). In this case I use a clock at 153600 Hz and a 16 divider in the...

Well I found it! The network is set up using a bat file which links the commands: - setting up environment variables - loading the packet driver - dhcp launch. On floppy disk a 'certain' time separates the different commands and it works, this time is shorter if I run the bat from the hd and...

Doing everything from floppies (boot and ftp networking) with exactly the same configuration (memory, drivers etc...) and it works ! Something is wrong on the dd.

Good morning, Quite suddenly (after formatting and a reinstallation of dos 6.22) my pc 80286 gives memory errors. The message is: ON BOARD PARITY ERROR ADDR(HEX) = (1000:2DF8) HALTED SYSTEM It's written in big letters. I think the message comes from the bios. CtrlAltDelete no longer gives...

Thanks !

Hi All, I search a Microsoft M80 assembler version (files or disk image) suitable for use with the Softcard into a IIe. I found several but I think there are not compatible with the Apple floppy format because as soon as I try to use I get "bdos error". All give the same problem at the same...

What I have not really understand is why is it a bigger problem for write than for read ? Because the operation which give problem under CPM is clearly read. May be write dont work but this do not hang CPM. May be its because the flip flop could be reset by R/W bus signal ? May be I will start...

In the same time this afternoon I give a close look to the FPU board and Microsoft Z80 board schematics and go to exactly the same conclusion... Arf !

Okay, great thanks. I have only 8 ways on my logic analyzer. I will probably made some read and write records of the data bus (D0 to D6) on AM9511 pins with the relevant clock first into 6502 mode. On your opinion what should I use as clock reference : phi0, phi1, Q3 ? Philippe

I cant see how this could be possible ??? I do more check yesterday and I can confirm that the board works very well in 6502 mode. I not only do a simple push pi but several successive operations into a basic program with a full success. I will give a last try from CPM with a different tool...

I do the test. Under CPM and GBasic I can peek without problem starting from $E600 to $E60F and the values are ok with the floppy controller rom listing. So basically peek works and address translation also. Now as soon as I try to read into the FPU board this evening some strange things...

Thanks for your help. The board is a rebuild of CCS APU 7811. The manual is here joined. Yes I can try to poke and peek in 'normal' memory addresses. I can do this test this evening but I have to find a suitable address to do so... $0100 to $93FF seems to be normally free under CPM. You...

All the bottom side (edge connector side) buttons of the switches are down so according to the manual seems to be off. I do the Z80 tests with Microsoft GBasic into CPM 2.23. Basically : first "POKE &HE091, &H1A" then 4 times "PEEK &HE090" to get the 4 top bytes of the stack. At this moment...

Your are right. I cross the addresses but just in the above message... During the test I use the correct values and I confirm that In 6502 mode : I can push $1A into $C091 then $C090 give the good result (pi in ieee notation). In Z80 mode : I also push $1A into $E091 and then E$090 give...

Forgot about this code. I do more simple tests... Just "by hand" write and read into the FPU board. I can access (either with the monitor or in Applesoft Basic with poke and peek) to the command / status register and to the in/out top data into the stack. In slot 1 I use $E090 (data) and...

Hello, My question is almost in the subject. I want to run some assembly code on a Z80 located in a Microsoft Softcard. This code include IN and OUT statement followed by a 8 bits address. I believe these instructions use the lower byte of the address bus and the ioreq pin of the Z80 to say...

In case of... Finally somebody located west of France found in his archive the 3 (ESS540, ESS541 and ESS542) original eprom dumps. I test them and they works well ! Now I am on the way to disassemble everything so Flex can be adapted again to the system. If you are interested feel free to...