Hi John /Neil, Sorry, didn't read Neils post close enough, Neil was referring to the Z80 Version 1 PCB, it's all clear now. FWIW I've looked at the Z80 V2 schematic and 8K page flips can be done with jumper changes and maybe one wire wrap connection Regards David Fry
On Saturday, March 22, 2014 7:12:29 AM UTC, David Fry wrote: > Hi John, > > I thought the Z80 V2 board flipped between 4k pages, > if it could do 8k pages then there would be enough ROM capacity in a > 28C256 for both the Z80 monitor and the Nascom Basic Neil is working on. > > regards > > David Fry > On Saturday, March 22, 2014 1:54:35 AM UTC, monahanz wrote: > >> FWIW, that’s actually one of the “improvements” on the V2 version of >> that board. >> >> >> http://s100computers.com/My%20System%20Pages/Z80%20Board/Z80%20CPU%20Board.htm#V2Z80 >> CPU Board >> >> >> >> John >> >> >> >> >> >> *From:* [email protected] [mailto:[email protected]] *On >> Behalf Of *David Fry >> *Sent:* Friday, March 21, 2014 3:59 PM >> *To:* [email protected] >> *Subject:* Re: [N8VEM-S100:2842] Re: BASIC in ROM - Any Interest? >> >> >> >> Hi Neil, >> >> >> >> Just throwing an idea out there, >> >> how about modifying the Z80 board to permit ROM page flipping between two >> 8k pages of a 28C256 (pin 1 - A14 of the 28C256 would be pulled high so >> only the top half of the 28C256 would be used) to permit the possibilty of >> jumping to Basic from a Z80 monitor menu option. When you're finished you >> hit reset and you're back at the Z80 monitor then you can boot into CP/M or >> what ever. The Z80 monitor would need to be updated to remove it's current >> page flip operation but I think that might make a great all in one solution. >> >> >> >> regards >> >> >> >> David fry >> >> >> On Friday, March 21, 2014 8:01:44 PM UTC, nbreeden wrote: >> >> Update for 3/21 >> >> >> >> I've uploaded information on the modification I made to the V1 Z-80 CPU >> Card to allow a full 8K EPROM to be addressed, look in the 'Builder >> Journals' area under 'Neil B'. >> >> >> >> BASIC Interpreter update: >> >> 2 minor bugs have been fixed. >> >> The input and crunch buffer lengths have been increased from 80 to 160 >> bytes. >> >> I picked 160 as increasing the buffer size takes away free memory >> for the BASIC program to reside in. >> >> I've moved the hardware specific portions (the I/O interfaces) into >> separate files to make adding new interfaces easier.. >> >> The build environment has been updated to support multiple I/O >> modules. >> >> Support for the following I/O sub-systems has been coded: >> >> N8VEM Serial I/O USB Adapter - Tested >> >> N8VEM Setial I/O SCC1 - Untested >> >> N8VEM Setial I/O SCC2 - Untested >> >> N8VEM Utility Board UART (16550) - Tested - This provides >> a model for 16550/16450/8250 UARTs >> >> -Neil >> >> -- >> You received this message because you are subscribed to the Google Groups >> "N8VEM-S100" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> For more options, visit https://groups.google.com/d/optout. >> > -- You received this message because you are subscribed to the Google Groups "N8VEM-S100" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
