Memory Top?

[James Harland]

Hi everyone,

This must be a really basic one, but I can't figure it out or find anything online.

When Searles BASIC starts up on my RC 2014 Classic ][, it asks "Memory Top?" I've been happily entering past this, but now I would like to set the RAMTOP so I can mess around with assembly inside my BASIC, but whatever non negative number I put into "Memory Top?" I just get "Memory Top?" again. I have discovered that a negative number or a numbe prefixed with 0x gets me a SN error.

So how do you enter something into Memory Top? or are you not supposed to?

Thanks,

James

[Spencer]

Hi James,

It's worth checking out the Nascom 2 BASIC manual which this version of BASIC is based on (with some screen and cassette routines removed)
https://archive.org/details/nascom-basic-manual/page/5/mode/1up although it is referenced as Memory Size rather than Memory Top

This version of BASIC uses 2s Compliment to address the 64k of memory, so you will need a number between -32768 and +32768

However, in my experience, just hitting return at that prompt always works fine :-)

Spencer 

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[aaw...@gmail.com]

Assuming it wants the last address to use for memory, enter 61439 (that is F000 hex converted to decimal -1)

Then start entering your program at F000 (or 61440 decimal).

[James Harland]

Thanks Spencer and aaw, but the problem is it doesn't seem to accept any numbers at all, it just loops back to the "Memory Top?" question until I enter nothing and hit enter. I'll share a screenshot later to show what I mean.

[James Harland]

This is what I mean:

[James Harland]

As a related question, does anyone know where USRLOC is in BASIC 4.7b which comes installed on the 32k Classic ][? It doesn't appear to be at 1004H and 1005H as per the Nascom 2 Microcomputer Documentation Appendix D.

[Phillip Stevens]

There is a full description of how to use the Searle MS BASIC adaption on the RC2014 Github.

The questions you have are answered there.

hexload readme

If you have the possibility to use the ROM from the MINI ][, I’d suggest that as the better starting point to use assembly with the RC2014 Classic ][ (the hardware is electrically identical).

The Mini ][ default ROM provides a number of levels of assembly support.

1. it has a simple assembly loader (MOKE) and reader (MEEP), which are multi-byte equivalents to POKE and PEEK.

2. there are precompiled ZEN assembler versions to allow you to edit, save, and load larger assembly programs. Various sizes are provided to allow larger or smaller space for simultaneous BASIC program usage.

3. there is a hex loading instruction HLOAD that receives Intel HEX and loads it into memory. It automatically adjusts the MEMTOP value to ensure that BASIC programs don’t overwrite the assembly, and automatically writes the USRLOC to enable you to start the program easily with ? USR(0). The companion RESET function returns the system to a cold start state without rebooting.

There are some other nice features like a startup BELL, memory testing, and the ability to program and use the RST locations via a jump table. And you can use it with an APU Module too. More information is in the README.

Any questions? Just ask. I’m still here.

feilipu

[James Harland]

Thanks feilipu! So I suppose the mini has your version 4.7c, or something like it? I've read about that on GitHub, sounds great!

Thanks for the link to the hexload page - for some reason I wasn't able to find that by Googling. I'll try it out this evening, or at the weekend.

Spencer - is there any chance I could somehow add a copy of the mini ][ default ROM to my next order, which will be the ROM burner for the Orton 3C? 

[James Harland]

OK so from the example feilipu linked to, I can see that the thing to do is to put in an integer higher than the 32382. By trial and error I have discovered that the smallest number it will accept is actually 33187, which will give you 32 bytes for BASIC. I am still a bit unsure how to address the memory you have then set aside for machine code, but it's good that I now know how to answer the "Memory top?" question!

[James Harland]

Yes, and now my question about USRLOC is answered - it's at &H8049 -, thanks again feilipu!

As a bonus I now know the syntax for writing hex directly into BASIC, which is a huge headache removed compared to having to use decimal, and DOKE is also super useful.

So my minimal "do nothing, but return safely" code works, hooray!

10 DOKE &H8049,&H9000
20 POKE &H9000,&HC9
30 PRINT USR(0)

[Spencer]

On Thursday, 29 January 2026 at 10:41, James Harland <harla...@gmail.com> wrote:

Spencer - is there any chance I could somehow add a copy of the mini ][ default ROM to my next order, which will be the ROM burner for the Orton 3C?

Hi James,

Yes. My first thought was just to add it from the listing on z80kits https://z80kits.com/shop/pre-programmed-rom/ but I'm glad I checked as that variation wasn't included there. I've updated that now, so you can just add it from there.

Cheers

Spencer

[Phillip Stevens]

On Friday, 30 January 2026 at 01:24:13 UTC+8 Spencer wrote:

On Thursday, 29 January 2026 at 10:41, James Harland wrote:

Spencer - is there any chance I could somehow add a copy of the mini ][ default ROM to my next order, which will be the ROM burner for the Orton 3C?

Yes. My first thought was just to add it from the listing on z80kits https://z80kits.com/shop/pre-programmed-rom/ but I'm glad I checked as that variation wasn't included there. I've updated that now, so you can just add it from there.

Spencer, it just occurred to me that the physical ROM devices may no longer be the same between Classic ][ and Mini ][, arising from the great ROM shortage. Is that so, or am I imagining it?

If so that would need to be accommodated on the order system too. (Yet another variation).

Cheers, P

[James Harland]

Thanks Spencer! So which ROM has the updated version of BASIC? Does it have the monitor too?