#garfield Logs

May 03 2021

12:10 AM rue_mohr: ooo
12:17 AM rue_mohr: oooooo
12:17 AM rue_mohr: I could maybe use a 16V8 as a readback register for the function call system I came up with
12:17 AM rue_mohr: it could do the address decode... maybe..
12:19 AM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1190406.jpg
12:19 AM rue_mohr: did you see how this works?
12:19 AM rue_mohr: its an interrupt call back system
12:20 AM rue_mohr: I write to a register, it stores the value for readback
12:20 AM rue_mohr: writing to it triggers a z80 mode 2 interrupt
12:20 AM aandrew: nope I didn't see that, that looks so wrong
12:20 AM rue_mohr: the z80 does a read cycle to get an offset for an interurpt vector table
12:20 AM aandrew: interesting
12:21 AM rue_mohr: the I register makes up the MSB, and that read makes up the LSB
12:21 AM rue_mohr: it loads a 16 bit address from that address and jumps to it
12:21 AM rue_mohr: so, I can do a function vector table with no instruction overhead
12:22 AM rue_mohr: I just write the index of the function I want to execute to the magic address
12:23 AM aandrew: yeah that is pretty slick
12:23 AM rue_mohr: to build it, I need a register (looping a 74ls574) OR gate for the magic read, and an address decoder, in this case a 74ls133 because I'm making the magic address FFF
12:24 AM rue_mohr: the most sig nibble is handled by the chip select chip (74ls138)
12:25 AM rue_mohr: I'm looking for ways to cut down the chip count, the inverter, and or gate are available from chips already installed
12:25 AM rue_mohr: the 74ls133 and 74ls574 need to be new
12:26 AM rue_mohr: I'm waiting for my new pins to arrive, getting low on the vero ones
12:26 AM rue_mohr: otherwise I'd be installing the 8254 for the baud gen
12:27 AM rue_mohr: there might not be a lot left of my old z80 when this is done
10:08 AM aandrew: rue_mohr: I'm not sure why but that pulls up a visual for me like a chicken carcass picked clean
05:02 PM polprog: https://i.ibb.co/Gnxgk8S/IMG-20210503-163708.jpg
05:02 PM polprog: https://i.ibb.co/C14GJKF/IMG-20210503-233459.jpg
05:03 PM polprog: ive done some baking today
05:21 PM aandrew: there are very, very few things better than a sandwich made with fresh baked bread
05:21 PM aandrew: good job polprog, now you need to ship me a loaf, I'm craving it like crazy
05:34 PM polprog: :)
05:35 PM polprog: i can send ya the recipe :)
05:35 PM aandrew: well no, I'm lazy too. :-)
05:35 PM polprog: ahh
05:36 PM polprog: well, i have a kitchen robot so i mostly had to mind the oven
05:36 PM aandrew: I can cook well and I can bake half decently. There are a lot of nice sourdough recipes that don't need kneading, it's one of the things on my list
05:37 PM polprog: i wanna try some shortbread cookies now. I heard the recipe is super easy
05:39 PM aandrew: my brother has my mom's teegeback recipe, and he's been perfecting it
05:39 PM aandrew: the single biggest trick is to take them out of the oven WAY earlier than you THINK you need to, the cook very fast
06:32 PM polprog: teegeback?
06:34 PM Tom_L: i would have to click on those sammiches right before dinner and food isn't ready
06:34 PM polprog: oops
06:35 PM polprog: thats too bad. I can tell you they are gone now, and im still hungry, if thats any consolation
06:35 PM Tom_L: none
06:36 PM Tom_L: not for me :)
06:36 PM aandrew: teegeback is german sugar/butter cookies, very much like shortbread
06:37 PM polprog: ahh
06:37 PM polprog: they sound tasty
06:38 PM polprog: is getting late, i think ill grab some tea and level myself
06:38 PM aandrew: they are also excellent with tea :-)
07:37 PM rue_mohr: so
07:37 PM rue_mohr: what if
07:37 PM rue_mohr: what if I took the memory space of my z80 and made it all ram
07:37 PM Tom_L: zram
07:38 PM rue_mohr: except a tiny little space at the boot vector that loaded the ram with an image from an i2c flash rom
07:38 PM rue_mohr: maybe even page that first bit
07:39 PM rue_mohr: so its all ram after boot
07:39 PM rue_mohr: except I want a paged lookup rom
07:40 PM rue_mohr: but that only needs 256 addresses
07:40 PM rue_mohr: hmm
07:41 PM rue_mohr: I wonder how long it would take a z80 to load all 512k of ram
07:51 PM rue_mohr: oh but I want nvram
08:06 PM Tom_L: how many cycles for read/write per byte?
08:11 PM rue_mohr: for ram?
08:18 PM Tom_L: to load from i2c to ram
08:20 PM rue_mohr: not sure
08:42 PM rue_mohr: not fast if I'm using bit banged i2c
08:43 PM rue_mohr: faster if I'm using something 3 wire based
08:43 PM Tom_L: makes sense
08:45 PM rue_mohr: I'll ponder it, all the bitwise instructions put the result in z, which is no good for shifting in data, which you need in C
08:46 PM rue_mohr: the only way I can see to move it, is to mask the byte with the i2c bit in it, and do an add with a number that trips C if the bit was a 1
08:46 PM rue_mohr: then shift that into the result reg
08:46 PM Tom_L: so drop to asm and do it
08:46 PM rue_mohr: or see if I have a 74ls299
08:47 PM rue_mohr: well, I need to work on other things first
08:47 PM rue_mohr: the pins didn't arrive today for for the comm chips
08:47 PM rue_mohr: so I'll put togethor the vection function system I dreamt up :)
08:49 PM Tom_L: is cold rolled steel the type with the bluish crust on it?
08:52 PM rue_shop1: it wouldn't have black crust
08:53 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/cnc/Mill_Steel/Assembly/Final/Strap_clamp.jpg
08:53 PM Tom_L: yes or no?
09:21 PM rue_shop1: I think it looks cold
09:21 PM rue_shop1: I made up the adatper for the other tank
09:21 PM rue_shop1: I'll test it tommorow and show you if it wroks :S
09:21 PM rue_shop1: I couldn't cut as much as I wanted cause of the existing threads
09:21 PM rue_shop1: they didn't have the adpater I wanted to to i with
09:23 PM Tom_L: cool
09:23 PM Tom_L: i'd make one for ya if i had a way to test the thread
09:24 PM rue_mohr: tis ok, external thread
09:25 PM rue_mohr: but I'd like to put a handle on the pulley of the lathe to make those easier to do by had
09:25 PM rue_mohr: hand
09:38 PM Tom_L: it doesn't have one?
09:38 PM Tom_L: oh, not the feed crank, the spindle pulley???
09:47 PM rue_shop1: yea
09:47 PM rue_shop1: so I can hand thread
09:49 PM Tom_L: removable i hope. doesn't sound like a good place for a permanent handle
09:58 PM rue_shop1: yea, unscrewable
10:10 PM rue_shop1: if I really want to mess up my memory map, I have a 356k ram chip
10:10 PM rue_shop1: er 256k
10:34 PM rue_mohr: so
10:34 PM rue_mohr: a trips b, trips c, trips d
10:34 PM rue_mohr: I need to wire to the data bus
10:34 PM rue_mohr: but I shouldn't do that without fixing the memory socket
10:35 PM rue_mohr: and if I'm doing that, I might as well upgrade the ram to 256k
10:35 PM rue_mohr: (from 64k+16k)
10:35 PM rue_mohr: which means changing up the way the address decoder works
10:35 PM rue_mohr: 8-S
10:35 PM rue_mohr: so
10:36 PM rue_mohr: small steps
10:39 PM rue_mohr: this is where the address map becomes so convoluded that I need a gal to sort it out
10:39 PM rue_mohr: another programmable thing
10:45 PM rue_mohr: so, later, I'll start with changing out the 74ls138 with a GAL16V8
10:47 PM rue_mohr: I have 128k un-accounted for
10:47 PM rue_mohr: hmm
10:47 PM rue_mohr: I might think of something later
10:48 PM rue_mohr: suddenly 512kbytes seems like a lot
10:48 PM rue_mohr: er
10:48 PM rue_mohr: 64kbytes
10:48 PM rue_mohr: 512kbits