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] <javascript:> [mailto: > [email protected] <javascript:>] *On Behalf Of *David Fry > *Sent:* Friday, March 21, 2014 3:59 PM > *To:* [email protected] <javascript:> > *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] <javascript:>. > 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.
