[Coco] 512K AND Beyond??? How FAR Beyond???

[Gene Heskett]

On Wednesday 27 December 2017 00:30:32 Allen Huffman wrote:

> On Dec 26, 2017, at 11:23 PM, Joe Schutts via Coco 
<coco at maltedmedia.com> wrote:
> > Another related question. If you have a 1 or 2 Meg system, is that
> > memory even accessible from Basic or does accessing it require OS-9
> > only (or NitroOS-9)??? Last question. Is it possible to access even
> > more memory (higher than 2 Meg) with a CoCo 3 and if so WHY hasn't
> > someone built (or even designed) a board and sell it here??? You
> > listening Ed??? Just kidding... Thanks Everyone...
>
> There was even an 8meg upgrade someone built.
>
> But no, stock BASIC won’t use it. Neither will OS-9. You had to have
> special patches for OS-9 and then it could. I do not know if anyone
> modified any of the BIG BASIC type programs for those upgrades, but
> OS-9ers made real good use of it.
>
> I am unaware of any software that was ever written to use it, though,
> Beyond OS-9, and even then, All it did was allow you to load more
> modules in memory at the same time, or have a larger RAM disk perhaps.
> Programs were still limited to fit within the 64K system area.

The program I wrote for a ramdisk, I called myram and which is now in the 
nitros hg pull, now renamed mram I believe, could be configured to use 
as much as 1.7 megs as a ramdisk. Its working size is determined by a 
byte in the descriptor that can be changed with dmode

This automatically formats itself on the first access, taking a few 
hundred milliseconds to do that, and when you are done with a big  
compile it could deiniz'd returning every byte to the  main memory pool.

I have a Disto 2 meg kit in mine. But it has not ran rsbasic in 10+ years 
because its invisible to basic.

> Though, Bank switching and stuff could have been used to get around
> that. I jus don’t think anyone needed it.

os9 level 2 is essentially a bank switching system, handling memory in 8k 
blocks, any 8 of which can be mapped into the processors 64k of address 
space at any one time. The patches to take it from 512k to 2048k of ram 
aren't terribly intrusive, mostly the change in the value of a byte in 
the init module, from $3F for a 512k system to $7F for a 1 meg, and $FF 
for a 2 meg system.  The multitasking in the clock module also manages 
the memory, and its possible to have 2 programs, each needing 56k of 
memory, in use, and talking to each other at the same time but it takes 
a lot of planning to pull that off.

Unfortunately, in the mad dash to break major modules down into separate 
modules to handle the os, and separate subroutines to address the 
hardware, it was not considered anything but good, until it was out of 
system ram because each such module requires another $27 bytes for its 
where is it tables so it knows where, and in what block of memory the 
next subroutine it needs has been loaded into. All that extra data 
cannot live outside of the processor address space, so for the last 
decade, I have not been able to format a floppy disk as that needs 
enough room in memory for a full track image, $6144 bytes, and about 
another kilobyte of scratchpad for the format program itself. So for 
about the last decade, by mb scripts have just erased what was on the 
disk, including the hidden boot track, so it can build a new disk on one 
that has already been formatted. It can even be done to a vdisk target 
thanks to the sh.dd which can be pointed at any of the vdisks, so I can 
do an mb without blinking a floppy drive led.  But guess what? The vdisk 
must be already formatted, and only 3 or 4 were ever formatted before 
format started failing by crashing the system, stepping on memory 
something else owned. So I have 2 hard drives of a gig each, but less 
than a meg of formatted space to play with. That rather resembles that 
famous rock and hard place scenario we're always being caught between. 

I fussed about this years ago when the breakup was being done, but to no 
avail. So it became ever more versatile until it was to me unusable.

Today, using bootlink, you only need one copy of the boot track, which 
could be on a floppy, because you can finish the boot using any one of 
the 255 vdisks of later versions of hdb-dos, to load the os9boot file 
from.

So stripped versions of the os9boot file can be made and used right on 
the hard drive simply by running bootlink to assign the next vdisk, and 
doing a powerdown reset. So I could "fix" my formatting problem, but 
about that time we had some water control work in the basement done to 
the tune of $12,000, (whee, no more flooding) which made such a mess 
scattering jackhammer dust over everything including the coco's, and the 
coco3 will not get powered up until I can take it and all its goodies to 
a high pressure air hose to clean it up. And the basement stairway is 
becoming a problem for this old (83 now) mans legs.

Those golden years they talked about? Only in the toilet bowl.

But I keep plugging along, careing for the missus who broke a hip last 
February, and because of her copd, isn't capable of doing for herself 
any more. So I play the part of a remote control, doing the housework 
that gets done, the cooking and laundry yadda yadda. Would I change 
that? Nope.

Now, I hope everyone has a better new year.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>