[Coco] Custom CoCo 3 ROM

[Dave Philipsen]

I have done a similar thing by modifying Brett Gordon's CoCoBoot for 
OS9. By holding down the ALT key while booting (on CoCo3FPGA or CoCoDEV) 
I can select an alternate boot file with which to boot OS9. It's handy 
but is considerably more involved than simply using a larger boot ROM 
(27512) and selecting whether the hi address line is at a logic "0" or "1".


On 11/21/2020 7:25 AM, Mathew Boytim via Coco wrote:
>   That is how the FreHD autoboot ROM's work for the Models 1/3/4 - if you hold down the spacebar it does its normal boot.  For coco users not familiar with the FreHD it's a popular hard drive emulator for the Models 1/3/4/4P.
> Matt
>      On Saturday, November 21, 2020, 07:46:18 AM EST, coco at jechar.ca <coco at jechar.ca> wrote:
>   
>   On 2020-11-20 11:02, Bruce W. Calkins wrote:
>> On 11/20/20 10:52 AM, tim lindner wrote:
>>> On Fri, Nov 20, 2020 at 7:34 AM <coco at jechar.ca> wrote:
>>>> I have a Coco whose 32K ROM is replaced by a Boot to Drivewire
>>>> ROM that only works to boot OS-9 from a drivewire server wondering
>>>> if there is a physical switch to allow one to switch between
>>>> two 32K ROMs so the original that has just bin sitting in a drawer
>>>> for years could be switched in to let me run COCO BASIC tape programs
>>>> and use game cartridges and Disk Basic.
>>> Maybe someone has a custom coco 3 rom that includes the default
>>> ability to DW Boot into OS-9?
>>>
>>> If you hold a key down, you get BASIC.
>>>
>>> Then you would not have to have a custom board made. All you would
>>> need to to reprogram the EEPROM you already have.
>>>
>> A more elegant solution, but someone do have to understand enough
>> assembly language to do it.
>>
>> Bruce W.
> That would be better.
>