If cassettes are giving you trouble then there is the option to replicate the ROM boot board : an easy way to get a simple monitor running in your machine.
With the finished schematics of backplane and decoder it is on with the hardware itself : fixed mains switch and tempguard, reconditioned main caps, checked main transistors, and presto : +5V is present ! Sometimes its easy....
But always keep in mind that the design is really very dangerous...
Yep, that seems to be the problem. The printer driver software is shifted by 4K.
Other potential pitfall : the 6850 needs to be the 2MHz variant, i.e. 68B50.
If alls fails : a very quick hack to obtain a programmable bit : add a 74ls74, with set and reset coupled to the 68B50. Reading/writing...
I will look into creating a guideline for using the RS232 interface.
However if you are only interested in toggeling a pin there is a wholly different approach possible : take a look at my 4052 RAMpack design, there I control the TTL counters directly from my 4052 machine. You have a RAM pcb...
And the final installment of my re-engineering efforts : schematics of the backplane, the decoder_iii and an updated schematic of the mainboard. Changes are mainly to do with naming consistency across the different schematics.
Also, for completeness sake, some pictures of the backpanel.
Note...
Hi Christian.
would you happen to still have software / documentation for that system ? I am located in Koblenz/Aargau and have the exact same setup here...
Jos Dreesen
Not sure what you mean by boot-routine. The initial loading from a mass storage device ? The manual describes this as the "restart" operation ( appendix A)
There we will need to check the firmware to locate that call. The machine I took the ROM from does not have tapes, therefore there must be...
Sorry, have missed this.
These manuals are now with me, as I have a running CPT9000 system. I suppose I could scan this material.
As already mentioned elsewhere on VCFED, i have some of the 9000 systemsoftware on my FTP site ftp://ftp.dreesen.ch/CPT
Looking for a CPT9000 keyboard. It does run...