RETRO-65C816

RETRO-65C816 Rev 1

Features

Design based on RETRO-EP4CE15 card
- Adds 65C816 CPU
- 5V level translator for keyboard
- 5V header moved to board edge
65C816 CPU
- 3.3V
- 8 MHz
- All pins are brought to FPGA
- Address A0-A15 and Data lines also go directly to the SRAM
- FPGA can have the ROM internally or download it to the SRAM
1MB SRAM
- 45nS access time
USB B
- FTDI USB to TTL
- Tx/Rx LEDs
VGA
- 2:2:2 R:G:B
PS/2 keyboard
- 5V KEYBOARD
- Level translator to 3.3V for FPGA
SD card socket
- Full-sized SD
QMTECH FPGA card mounts on top
95x95mm card
- ODAS form factor
(4) 6-32 Mounting holes

65C816 CPU

65C816 Datasheet

Block Diagram

Timing

Connectors

H1 - 5V

Install jumper to power card from USB

H2 - VREG I/O Conn

Power to J1

J1 - I/O Connector

50-pin I/O Connector

J2 - Keyboard

1x4 header

J3 - 6 FPGA pins

J4 - USB B Serial/Power

Serial to/from FTDI
Can power the card

J5 - 5V/GND

5V/ground for external 5V logic

J7 Pin Mapping Card to FPGA pins - Right connector

U7 PIN	EP4CE15	EP4CE55	5CEFA2	CYC 10	FUNCTION	U7 PIN	EP4CE15	EP4CE55	5CEFA2	CYC 10	FUNCTION
1	GND	GND	GND	GND	GND	2	GND	GND	GND	GND	GND
3	3.3V	3.3V	3.3V	3.3V	3.3V	4	3.3V	3.3V	3.3V	3.3V	3.3V
5	GND	GND	GND	GND	GND	6	GND	GND	GND	GND	GND
7	PIN_R1	PIN_R1	PIN_AA2	PIN_G1	PS2CLK	8	PIN_R2	PIN_R2	PIN_AA1	PIN_G2	PS2DAT
9	PIN_P1	PIN_P1	PIN_Y3	PIN_D1	SRAMA4	10	PIN_P2	PIN_P2	PIN_W2	PIN_C2	SRAMA5
11	PIN_N1	PIN_N1	PIN_U1	PIN_B1	SRAMA3	12	PIN_N2	PIN_N2	PIN_U2	PIN_F5	SRAMA6
13	PIN_M1	PIN_M1	PIN_N1	PIN_D3	SRAMA2	14	PIN_M2	PIN_M2	PIN_N2	PIN_C3	SRAMA7
15	PIN_J1	PIN_J1	PIN_L1	PIN_B3	SRAMA1	16	PIN_J2	PIN_J2	PIN_L2	PIN_A3	SRAM0E_N
17	PIN_H1	PIN_H1	PIN_G1	PIN_B4	SRAMA0	18	PIN_H2	PIN_H2	PIN_G2	PIN_A4	SRAMA8
19	PIN_F1	PIN_F1	PIN_E2	PIN_E5	SRAMCS_N	20	PIN_F2	PIN_F2	PIN_D3	PIN_A2	SRAMD7
21	PIN_E1	PIN_E1	PIN_C1	PIN_D4	SRAMD0	22	PIN_D2	PIN_D2	PIN_C2	PIN_E6	SRAMD6
23	PIN_C1	PIN_C1	PIN_G6	PIN_C6	SRAMD1	24	PIN_C2	PIN_C2	PIN_H6	PIN_D6	SRAMD5
25	PIN_B1	PIN_B1	PIN_G8	PIN_B5	SRAMD2	26	PIN_B2	PIN_B2	PIN_H8	PIN_A5	SRAMD4
27	PIN_B3	PIN_B3	PIN_F7	PIN_B6	SRAMD3	28	PIN_A3	PIN_A3	PIN_E7	PIN_A6	SRAMA9
29	PIN_B4	PIN_B4	PIN_D6	PIN_B7	SRAMWE_N	30	PIN_A4	PIN_A4	PIN_C6	PIN_A7	SRAMA10
31	PIN_C4	PIN_C4	PIN_E9	PIN_D8	SRAMA19	32	PIN_C3	PIN_C3	PIN_D9	PIN_C8	SRAMA11
33	PIN_B5	PIN_B5	PIN_B5	PIN_D9	SRAMA18	34	PIN_A5	PIN_A5	PIN_A5	PIN_C9	SRAMA12
35	PIN_B6	PIN_B6	PIN_B6	PIN_B8	SRAMA17	36	PIN_A6	PIN_A6	PIN_B7	PIN_A8	SRAMA13
37	PIN_B7	PIN_B7	PIN_A7	PIN_B9	SRAMA16	38	PIN_A7	PIN_A7	PIN_A8	PIN_A9	SRAMA14
39	PIN_B8	PIN_B8	PIN_A9	PIN_E9	N/C	40	PIN_A8	PIN_A8	PIN_A10	PIN_E8	SRAMA15
41	PIN_B9	PIN_B9	PIN_B10	PIN_E11	CARDDET	42	PIN_A9	PIN_A9	PIN_C9	PIN_E10	N/C
43	PIN_B10	PIN_B10	PIN_G10	PIN_A10	USBRX/FPGATX	44	PIN_A10	PIN_A10	PIN_F10	PIN_B10	USBCTS/FPGARTS
45	PIN_B13	PIN_B13	PIN_C11	PIN_D12	USBTX/FPGARX	46	PIN_A13	PIN_A13	PIN_B11	PIN_D11	UBSRTS/FPGACTS
47	PIN_B14	PIN_B14	PIN_B12	PIN_B11	REDHI	48	PIN_A14	PIN_A14	PIN_A12	PIN_A11	REDMID
49	PIN_B15	PIN_B15	PIN_E12	PIN_B12	REDLO	50	PIN_A15	PIN_A15	PIN_D12	PIN_A12	GRNHI
51	PIN_B16	PIN_B16	PIN_D13	PIN_B13	GRNMID	52	PIN_A16	PIN_A16	PIN_C13	PIN_A13	GRNLO
53	PIN_B17	PIN_B17	PIN_B13	PIN_B14	BLUHI	54	PIN_A17	PIN_A17	PIN_A13	PIN_A14	BLULO
55	PIN_B18	PIN_B18	PIN_A15	PIN_D14	HSYNC	56	PIN_A18	PIN_A18	PIN_A14	PIN_C14	VSYNC
57	PIN_B19	PIN_B19	PIN_B15	PIN_B16	SDCS_N	58	PIN_A19	PIN_A19	PIN_C15	PIN_A15	SD_MOSI
59	PIN_B20	PIN_B20	PIN_C16	PIN_C16	SD_SCK	60	PIN_A20	PIN_A20	PIN_B16	PIN_C15	SD_MISO
61	GND	GND	GND	GND	GND	62	GND	GND	GND	GND	GND
63	VIN	VIN	VIN	VIN	VIN	64	VIN	VIN	VIN	VIN	VIN

J8 Pin Mapping Card to FPGA pins - Left connector

U8 PIN	EP4CE15	EP4CE55	5CEFA2	10C1006	J1	Function	U8 PIN	EP4CE15	EP4CE55	5CEFA2	10C1006	J1	Function
1	GND	GND	GND	GND	N/C		2	GND	GND	GND	GND	N/C
3	3.3V	3.3V	3.3V	3.3V	J1-1		4	3.3V	3.3V	3.3V	3.3V	J1-2
5	GND	GND	GND	GND	N/C		6	GND	GND	GND	GND	N/C
7	PIN_AA13	PIN_AA13	PIN_AA14	PIN_R9	N/C	CPUE	8	PIN_AB13	PIN_AB13	PIN_AA13	PIN_T9	N/C	CPURES*
9	PIN_AA14	PIN_AA14	PIN_AA15	PIN_R10	J1-4	CPUMX	10	PIN_AB14	PIN_AB14	PIN_AB15	PIN_T10	J1-3	CPUCLK
11	PIN_AA15	PIN_AA15	PIN_Y15	PIN_R11	J1-6	CPUBE	12	PIN_AB15	PIN_AB15	PIN_Y13	PIN_T11	J1-5	CPUNMIB
13	PIN_AA16	PIN_AA16	PIN_AB18	PIN_R12	J1-8	CPURWB	14	PIN_AB16	PIN_AB16	PIN_AB17	PIN_T12	J1-7	CPUIRQB
15	PIN_AA17	PIN_AA17	PIN_Y7	PIN_N9	J1-10	CPUVDA	16	PIN_AB17	PIN_AB17	PIN_Y16	PIN_M9	J1-9	CPUABORTB
17	PIN_AA18	PIN_AA18	PIN_AA18	PIN_M10	J1-12	CPUVPA	18	PIN_AB18	PIN_AB18	PIN_AA17	PIN_P9	J1-11	CPURDY
19	PIN_AA19	PIN_AA19	PIN_AA20	PIN_P11	J1-14	CPUVPB	20	PIN_AB19	PIN_AB19	PIN_AA19	PIN_N11	J1-13	CPUMLB
21	PIN_AA20	PIN_AA20	PIN_Y20	PIN_R13	I1-16		22	PIN_AB20	PIN_AB20	PIN_Y19	PIN_T13	J1-15
23	PIN_Y22	PIN_Y22	PIN_AB21	PIN_T15	J1-18		24	PIN_Y21	PIN_Y21	PIN_AB20	PIN_T14	J1-17
25	PIN_W22	PIN_W22	PIN_AA22	PIN_N12	J1-20		26	PIN_W21	PIN_W21	PIN_AB22	PIN_M11	J1-19
27	PIN_V22	PIN_V22	PIN_W22	PIN_R14	J1-22		28	PIN_V21	PIN_V21	PIN_Y22	PIN_N13	J1-21
29	PIN_U22	PIN_U22	PIN_Y21	PIN_N14	J1-24		30	PIN_U21	PIN_U21	PIN_W21	PIN_P14	J1-23
31	PIN_R22	PIN_R22	PIN_U22	PIN_P16	J1-26		32	PIN_R21	PIN_R21	PIN_V21	PIN_R16	J1-25
33	PIN_P22	PIN_P22	PIN_V20	PIN_N16	J1-28		34	PIN_P21	PIN_P21	PIN_W19	PIN_N15	J1-27
35	PIN_N22	PIN_N22	PIN_U21	PIN_M16	J1-30		36	PIN_N21	PIN_N21	PIN_U20	PIN_M15	J1-29
37	PIN_M22	PIN_M22	PIN_R22	PIN_L16	J1-32		38	PIN_M21	PIN_M21	PIN_T22	PIN_L15	J1-31
39	PIN_L22	PIN_L22	PIN_P22	PIN_P15	J1-34		40	PIN_L21	PIN_L21	PIN_R21	PIN_M12	J1-33
41	PIN_K22	PIN_K22	PIN_T20	PIN_L14	J1-36		42	PIN_K21	PIN_K21	PIN_T19	PIN_L13	J1-35
43	PIN_J22	PIN_J22	PIN_P16	PIN_K16	J1-38		44	PIN_J21	PIN_J21	PIN_P17	PIN_K15	J1-37
45	PIN_H22	PIN_H22	PIN_N20	PIN_K12	J1-40		46	PIN_H21	PIN_H21	PIN_N21	PIN_J12	J1-39
47	PIN_F22	PIN_F22	PIN_M21	PIN_J14	J1-42		48	PIN_F21	PIN_F21	PIN_M20	PIN_J13	J1-41
49	PIN_E22	PIN_E22	PIN_M18	PIN_K11	J1-44		50	PIN_E21	PIN_E21	PIN_N19	PIN_J11	J1-43
51	PIN_D22	PIN_D22	PIN_L18	PIN_G11	J1-46		52	PIN_D21	PIN_D21	PIN_L19	PIN_F11	J1-45
53	PIN_C22	PIN_C22	PIN_M22	PIN_F13	J1-48		54	PIN_C21	PIN_C21	PIN_L22	PIN_F14	J1-47
55	PIN_B22	PIN_B22	PIN_L17	PIN_F10	N/C		56	PIN_B21	PIN_B21	PIN_K17	PIN_F9	N/C
57	PIN_N20	PIN_N20	PIN_K22	PIN_E16	N/C		58	PIN_N19	PIN_N19	PIN_K21	PIN_E15	N/C
59	PIN_M20	PIN_M20	PIN_M16	PIN_D16	N/C		60	PIN_M19	PIN_M19	PIN_N16	PIN_D15	N/C
61	GND	GND	GND	GND	J1-50		62	GND	GND	GND	GND	J1-49
63	+5V	+5V	+5V	+5V	J1-50		64	+5V	+5V	+5V	+5V	J1-50

P1 - VGA

DB-15HD connector
3:3:2 R:G:B

P2 - PS/2 Keyboard

Purple DIN-6 for PS/2 keyboard

P4 - SD Card

Mechanicals

MultiComp On RETRO-65C816 VHDL Code

MultiComp On RETRO-65C816 GitHub page

References/Notes

On the usefulness of 65816 as a 65C02 alternative
- Helpful timing information

...potential for data bus contention during Ø2 low. My solution was two-fold: use VDA and VPA to qualify chip selects, and qualify read-accesses with Ø2. The former assures that an addressed device will not respond to selection until the address bus is truly valid—invalid bus states may occur during the execution of some instructions. The latter assures that a selected device will not drive the data bus when the '816 is presenting A16-A23 on it. This solution doesn't totally eliminate the risk of contention but greatly narrows the window of opportunity for it. The need for more stringent qualifying of D0-D7 would depend on the peripheral silicon on the bus. In the case of POC and the Ø2 rate I'm using (12.5 MHz maximum), everything gets off the data bus before the '816 starts to drive it with the bank address. That would not be the case if I were to increase Ø2 to 20 MHz, however.

Floating the buses with BE creates the odd situation where no valid address exists on A0-A15, which I daresay could cause a device to be selected solely because of a residual charge in bus capacitance. Also, BE floats the RWB signal*, which may trip up other logic that is dependent on RWB always being driven to one state or the other. The most fool-proof solution is the use of a data bus transceiver as you suggested, which is a straightforward method (74AC245 or 74AHC245 recommended if Ø2 will exceed 8 MHz).

Revision History

Rev 2

Fixed W65C816 footprint
- Bigger footprint
- Moved around a lot of tracks to remove ground trace and use ground plane
Changed from 2:2:2 to 3:3:2 bit video (256 colors)
Changed J1 pinout to not use 2 input-only J8 pins
Shuffled J7 pinout

Rev 1

W65C816 footprint is too small for part
- Used TQFP footprint but part is clearly too big
- Datasheet does not indicate package detail
- 0.8mm pitch was OK
Works well as RETRO-EP4CE15 replacement
- PS/2 @5V is good