MSX eprom cart for testing?

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By NYYRIKKI

Enlighted (5366)

NYYRIKKI's picture

05-05-2014, 15:12

ericb59 wrote:

What are the meaning of the straps on your board ?

P1+  = PIN1 is connected to 5V
P1-  = PIN1 is connected to GND

CS1  = select #4000-#7FFF
CS2  = select #8000-#BFFF
CS3  = select #4000-#BFFF (AKA CS12 ...more like CS21)

128k     = Pin27 = /Pgm = 5V
256/512k = Pin27 = A14

Please note: Although there reads 512k this board is not really optimal for 48KB/64KB programs as there is no connection from A15. Pin1 is fixed.

By roadfighter

Champion (388)

roadfighter's picture

05-05-2014, 20:37

NYYRIKKI wrote:

Please note: Although there reads 512k this board is not really optimal for 48KB/64KB programs as there is no connection from A15. Pin1 is fixed.

I know, but if you put 2 programs of 32k in the 512K eprom you can switch between the 2 programs by switching the jumper P1 + and P1-.
Made a PDF. for it MSX Eprom Print

ericb59 wrote:

What are the meaning of the straps on your board ?
How much do you sell them ?

Nyyrikki made the straps clear i hope, or my PDF does B-)
And i have still some for sale, 1pcb for 3euros and 5 pcbs for 13,50 euros.and shipping in Europe as a letter is 3,15 euro.
Not a lot left do :P

By NYYRIKKI

Enlighted (5366)

NYYRIKKI's picture

06-05-2014, 05:46

Yes, and if someone really needs real 512k ROM-mode (Universe:Unknown, Zombie Incident, The Cure, Alter ego etc.) it is really not that complicated:

By ericb59

Paladin (859)

ericb59's picture

06-05-2014, 07:56

@Nyyrikki I d'ont understand why you are talking about a 512k ROM for a game like, THE CURE.
This Rom is 48K, it don't need 512K room space ?

By NYYRIKKI

Enlighted (5366)

NYYRIKKI's picture

06-05-2014, 08:18

512Kb <> 512KB

By ericb59

Paladin (859)

ericb59's picture

06-05-2014, 08:24

Confused Shocked! Shocked! Smile
512Kb=64KB

By NYYRIKKI

Enlighted (5366)

NYYRIKKI's picture

06-05-2014, 08:35

Yes... That is why they call 128KB ROMs as Mega ROMs (1Mb)

By Grauw

Ascended (8406)

Grauw's picture

06-05-2014, 10:37

I never saw the point in speaking about ROM sizes in terms of megabits. At least for me it is not intuitive, I always have to make a mental conversion. Maybe because it sounded more impressive or something? But anyway…

By Huey

Prophet (2644)

Huey's picture

06-05-2014, 10:45

Marketing for sure.

By NYYRIKKI

Enlighted (5366)

NYYRIKKI's picture

06-05-2014, 13:32

I kind of understand why ROM sizes are in megabits... Bytes are not very practical in electronics. ie. MSX VRAM is typically only 4bits wide. Converting that size to bytes would not make much sense. Even in computers the bytes have not always been such a big standard as it is today. ie. legendary PDP-1 worked with 18bit words using 6bit wide memories -> Talking about 8bit bytes would be pretty pointless.

How ever while all other MSX marketing was already talking about kilobytes (like "MSX has 32KB of ROM + 80KB of RAM") and only big ROM games were measured in kilobits I would say it was more just marketing trick rather than reasonable... How ever we see this same still today. ie. speeds are measured in megabits while the transferred data is measured in megabytes.

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