Search found 490 matches

by marcelk
01 Apr 2020, 12:10
Forum: Hardware and software hacking
Topic: Alternative Languages
Replies: 4
Views: 3153

Re: Alternative Languages

For vCPU we purposely went for a model that encourages to put everything important on fixed locations in zero page. For small programs on small computers, that is perfectly fine. And that's why the GCL notation doesn't even bother with scoping. Still you can do recursion if you want, using LDWL, STW...
by marcelk
27 Mar 2020, 06:06
Forum: Hardware and software hacking
Topic: Python Assembler Query - RAM labels
Replies: 10
Views: 5694

Re: Python Assembler Query - RAM labels

Perhaps ASM.py can be modded to warn on page faults for branches. That's a good point. There's a small dilemma here between chopping off the high byte when resolving symbols, vs. requiring the high byte to be zero or match the page number. We chop off the high byte now because that has many uses. d...
by marcelk
26 Mar 2020, 09:49
Forum: Hardware and software hacking
Topic: Python Assembler Query - RAM labels
Replies: 10
Views: 5694

Re: Python Assembler Query - RAM labels

This is a long time ago.... Internally the ROM bytes are kept in two lists, _rom0 and _rom1 for the even and odd bytes. _romSize = 0 _rom0, _rom1 = [], [] This goes back to the breadboard with two 28C64 chips: ROM0_ROM1.jpeg The way it is now, _rom0 and _rom1 start out empty and the assembler append...
by marcelk
24 Mar 2020, 16:03
Forum: Hardware and software hacking
Topic: v6502 mini-assembler in Apple-1 emulator
Replies: 3
Views: 4714

Re: v6502 mini-assembler in Apple-1 emulator

The mini-assembler's usage is now displayed when starting it with EEER. But you can skip this with an easy-to-remember alternative entry point. When toying with 6502 code and making mistakes, the system appears more stable than I expected. This is because in v6502 practically all invalid instruction...
by marcelk
24 Mar 2020, 09:01
Forum: Hardware and software hacking
Topic: Interrupts:
Replies: 11
Views: 8775

Re: Interrupts:

marcelk wrote: 18 Feb 2020, 11:34 After experiencing the impact on Apple-1 Integer BASIC, I'm strongly thinking to move the $00FC-$00FF vIRQ locations to $0030-$0033. Any objections, please shoot...
Relocation is now done including documentation and example code. This also fixed `AUTO'.
by marcelk
22 Mar 2020, 07:59
Forum: Escape Meta Alt Control Shift
Topic: Two years of kit making and Open Source Hardware
Replies: 7
Views: 4569

Re: Two years of kit making and Open Source Hardware

Although we don't "target" schools at all, quite a few buyers are teachers and school departments! We have plenty of ideas, big and small. But an idea is of very little value unless you commit to it yourself. For example, I'ld love to build a discrete transistor Gigatron at full speed. But something...
by marcelk
21 Mar 2020, 06:33
Forum: Escape Meta Alt Control Shift
Topic: Two years of kit making and Open Source Hardware
Replies: 7
Views: 4569

Re: Two years of kit making and Open Source Hardware

jbailey wrote: 21 Mar 2020, 01:36 How many kits have you guys sold to date?
We're currently somewhere between the Apple-1 and Apple ][ :-)
by marcelk
20 Mar 2020, 18:36
Forum: Escape Meta Alt Control Shift
Topic: Two years of kit making and Open Source Hardware
Replies: 7
Views: 4569

Two years of kit making and Open Source Hardware

Two years ago this week we started sending out the first "real" Gigatron kits to enthousiasts on our waiting list. Those early kits came with ROM v1, without Tiny BASIC, without Pluggy McPlugface, and without video reviews on YouTube. Originally we aimed for February 2018 as release month. But after...
by marcelk
20 Mar 2020, 07:49
Forum: Hardware and software hacking
Topic: Python Assembler Query - RAM labels
Replies: 10
Views: 5694

Re: Python Assembler Query - RAM labels

I split the topic for easier later reference: https://forum.gigatron.io/viewtopic.php?f=4&t=218 TL;DR: Those long sequences of 'ld $dd' instructions in the file storage area of the EPROM aren't executed in sequence at all. They are all single-instruction subroutines that each carry a single data byte.
by marcelk
20 Mar 2020, 07:11
Forum: Hardware and software hacking
Topic: Reading from ROM, LUP and trampolines
Replies: 2
Views: 2679

Reading from ROM, LUP and trampolines

Can you perhaps explain trampolining a little...? :oops: Let's take some steps back first before jumping to the trampolines. Originally in the breadboard computer the [Y,X++] mode was supposed to serve two purposes: Purpose 1. Streaming pixels to OUT ld [Y,X++],OUT ld [Y,X++],OUT ld [Y,X++],OUT ......