Re: [N8VEM-S100:2842] Re: BASIC in ROM

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#V2 Z80 CPU Board

John

From: n8ve...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of David Fry
Sent: Friday, March 21, 2014 3:59 PM
To: n8ve...@googlegroups.com
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

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